6
THE NATURAL HISTORY OF THE COMMON CRAYFISH.
general hue may be reel or blue.
These are “ cray¬
fishes,” and they cannot possibly be mistaken for any other inhabitants of our fresh waters.
Fig. 1.—Astac.ns fluviatilis.—Side view of a male specimen (nat. size):— bg, branchiostegite ; eg, cervical groove ; r, rostrum ; t, telson.— 1, eye-stalk ; 2, antennule; 3, antenna ; 9, external maxillipede ; 10, forceps; 14, last ambulatory leg; 17, third abdominal ap¬ pendage ; 20, lateral lobe of the tail-fin, or sixth abdominal appendage ; xv, the first ; and xx, the last abdominal somite. In this and in succeeding figures the numbers of the somites are given in Roman, those of the appendages in ordinary numerals.
The animals may he seen walking along the bottom of the shallow waters which they prefer, by means of four pairs of jointed legs (fig. 1); but, if alarmed, the}^ swim
