On the Variations of certain Crustacea. 383 



slight inequality of the valves is very general aniongst the 

 Ostracoda, there are some species which possess this character 

 strongly developed, and are at the same time not at all refer- 

 able to the genus Bairdia. Cythere convexa, Baird, is a well- 

 marked example, the carapace having the general form of 

 Bairdia, and also the unequal and overlapping valves, but 

 exhibiting at the same time the strongly- developed hinge-pro- 

 cesses of Cythere. 



It may also be noted as a most interesting fact that there 

 exist several genera of marine Ostracoda — not hitherto de- 

 scribed as British* — which are distinctly intermediate, in the 

 character of the contained animals, between the (chiefly) 

 marine ambulatory genus Cythere, and the purely fresh water, 

 natatory genus Gypris. These intermediate genera are — 

 Bairdia, Pontocypris, Paracypris, and Argilloecia. The first- 

 named group is represented in the British seas by several 

 species, B. inflata, Norman; B. acanthigera, Brady ; B. inter- 

 media, Brady ; B. obtusata, G. O. Sars ; B. minna, Baird. Of 

 Paracypris, we have one British species, P. polita, G. 0. Sars ; 

 of Pontocypris two species, P. semilafa, G. 0. Sars ; and P. 

 trigonella, G. 0. Sars, while the genus Argilloecia seems to be 

 unrepresented on our shores. 



The object which I have now more especially in view is to 

 give a brief abstract of a memoir recently published by Dr. 

 ClausJ on the Copepoda of Nice. This paper has not, so far 

 as I know, been yet translated, or even noticed, in England. 

 The object of the author, besides the description of new species, 

 was to give an account of some remarkable variations which 

 have come under his notice during a long study of this tribe 

 of animals, and I propose now to notice, very briefly, some of 

 the facts which he describes. 



The Copepoda of Nice, are, as might be expected from 

 geographical considerations, much more nearly related to those 

 of Messina than to those of the North Sea, but the following- 

 particularly northern forms are found likewise at Nice : — ■ 

 Anomalocera Pater sonii, an Atlantic Pontella, Cetochilus sep- 

 tentrionalis, which forms the chief food of the Arctic whales, 

 but attains in that northern region to a much greater size ; also 

 Tishe furcata and Euterpe gracilis. Other species occur less 

 commonly, such as Ichthyophoroa denticornis, of which the Nice 

 variety is of strikingly slender form, and has, in the male, 

 remarkably small clasping feet. The variations noticed in 

 Bias longiremis are also remarkable. 



* Some of these species have been described from the external shell charac- 

 ters by British authors, but of the animals themselves nothing has been published 

 in this country. 



X " Die Copepoden-Eauna von Kizza : ein Beitrag zur cViaraltteristik der formen 

 und deren Abiinclerungen im sinne Darwin's." Marburg unci Leipzig, 1S66. 



