Page:VCH Warwickshire 1.djvu/218

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A HISTORY OF WARWICKSHIRE cephalic crest. * The head, in fact, presents the form of a hood more or less curved in a dorsal direction, laterally flattened. Thus the ventral margin forms a regularly convex line, while the dorsal margin is con- cave. The head attains half the length of the body (not including the caudal spine, which is almost as long as the head).' He does not accept any English locality for it, but believes the form commonly noted under the name cederstromii to be a variety of H, jardinii, for which he proposes the name incerta on account of the uncertainties arising from its confusion with the true cederstromii^ The upshot of all these explanations is to credit Warwickshire with Daphnia pulex, var. brevispina, Daday de Dees ; Z). longispina, O. F. M tiller ; D. galeata, Sars ; Hyalodapbnia jardinii, var. incerta, Richard ; and H. kablbergiensis, Schodler. According to Lilljeborg, in his important work just issued, the last of these should be called Daphnia (Hyalodaphnia] cucullata, Sars. 1 It is indeed only in Utopia that the student can expect to rest and be thankful over a final settlement of zoological names. Belonging to the same family of the Daphniida? Mr. Hodgson records Simocepbalus ve'tu/us (O. F. Miiller), * abundant in clear weedy water, canals'; Scapholeberis mucronata (O. F. M.), ' common : Olton, Kingswood, Middleton, Hagley Park ' ; Ceriodaphnia reticulata (Jurine), 'Middleton, Olton'; C. rotunda (Straus), 'generally distributed'; C. quadrangula (O. F. M.), ' Barnt Green, Middleton'; C. megalop s, Sars, ' Lower Bittel Reservoir, Olton Mill' ; and Moina rectirostris (O. F. M.), ' a horsepond near Harborne.' All these genera were at one time included under Daphnia, and the first three of them still were so in 1850 when the Ray Society published Dr. Baird's valuable book on The Natural History of the British Entomostraca. In that volume Baird distinguished Moina, which has the first antennae of the female long and inserted on each side of the head's ventral margin, from the other Daphniidae, in which these antennae are small and inserted under the rostrum or on the head's hind margin. Simocepbalus, Schodler, has its shell covering marked with sub-parallel transverse lines, whereas in Daphnia and others there is a reticulation of little quadrate or polygonal meshes. In Ceriodaphnia, Dana, the first antenna? of the female are movable, while in Daphnia and Hyalodaphnia they are immovable, and from these three Scapholeberis, Schodler, is differentiated by having the ventral margin almost straight in continuity with the caudal spine, and by having a distinct hind margin. In the others the convex ventral and dorsal margins meet at the caudal spine, so that the hind margin remains undefined as in the bow of a boat. In the family Bosminida? the records are Eosmina longirostris (O. F. Mtiller) and B. longispina, Leydig, of which the former is said to have the 'head erect, not tumid above,' the latter to have the 'head depressed, tumid above.' It may be worth while here to notice that in describing 1 Ann. Set. Nat. ser. 8, ii. 331, 343 (1896). 8 ClaJocera Sueci*, p. 127. 1 80