Page:Geological Evidences of the Antiquity of Man.djvu/227

We are indebted to Mr. Searles Wood, F.G.S., for an admirable monograph on the fossil shells of these British pliocene formations. He has not himself given us an analysis of the results of his treatise, but the following tables have been drawn up for me by Mr. S. P. Woodward, the well-known author of the 'Manual of the Mollusca, Recent and Fossil' (London, 1853–6), in order to illustrate some of the general conclusions to which Mr. Wood's careful examination of 442 species of mollusca has led.

 

Number of known Species of Marine Testacea in the three English Pliocene Deposits, called the Norwich, the Red, and the Coralline Crags.

1. Brachiopoda ................................................................................................................................................................................................................................................................................................................................................................................................

   6

1. Conchifera ................................................................................................................................................................................................................................................................................................................................................................................................

   206

1. Gasteropoda ................................................................................................................................................................................................................................................................................................................................................................................................

   230

——

1. ⁠Total ................................................................................................................................................................................................................................................................................................................................................................................................

   42

——

 

Distribution of the above Marine Testacea.

Number of Species.

Species common to the

1. Norwich Crag81

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Red Crag225

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Coralline Crag327

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Norwich and Red Crag (not in Cor. )33

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Norwich and Coralline (not in Red)4

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Red and Coralline (not in Norwich)116

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Norwich, Red, and Coralline19^[1]

   ................................................................................................................................................................................................................................................................................................................................................................................................

 

Proportion of Recent to Extinct Species.

Recent.
⁠

1. Norwich Crag69

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Red Crag130

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Coralline Crag168

   ................................................................................................................................................................................................................................................................................................................................................................................................

Extinct
⁠

1. 12

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. 95

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. 159

   ................................................................................................................................................................................................................................................................................................................................................................................................

Per-centage of⁠
Recent.⁠

1. 85

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. 57

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. 51

   ................................................................................................................................................................................................................................................................................................................................................................................................

 

Recent Species not living now in British Seas.

Northern Species.
⁠

1. Norwich Crag12

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Red Crag8

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. Coralline Crag2

   ................................................................................................................................................................................................................................................................................................................................................................................................

Southern.
⁠

1. 0

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. 16

   ................................................................................................................................................................................................................................................................................................................................................................................................

1. 27

   ................................................................................................................................................................................................................................................................................................................................................................................................

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1. These 19 species must be added to the numbers 33, 4, and 116 respectively in order to obtain the full amount of common species in each of those cases.