Miscellaneous. 23 1 



liaVkul. One of the Scaudinavian species, Gammurun {Pallasea) 

 cancelloldes, occurs also in Siberia ; another, Oamuiarus neylectus, 

 is scarcely distinct from Oammarus ptdex, which forms part of the 

 fauna of Lake Baikal. If we compare the relative number of 

 genera admitted by the two authors, we find a remarkable differ- 

 ence ; thus i)r. Dybowsky only admits two genera for his 97 species 

 (Gamma nis 90 species, C'oiistantia, g. n., 1 species), whUe the four 

 species of M. Sars belong to four ditlerent genera. liut the genus 

 is something much more subjective than the species ; and we have uo 

 doubt that, if treated by some authors (Mr. S;)ence Bate, for ex- 

 ample), the Gammaridte of Lake Baikal would have furnished 

 materials for the creation of numerous generic groups. Gamniarus 

 canceUoules, Gerstf., retained by Dr. Dybowsky in its original genus, 

 is the Pallasea canctlloides of Spence Bate and Sars. 



Dr. Dybowsky explains the reason why he has not dismembered 

 the genus Gam mar as — namely, that the modifications observed in 

 the different parts of the body present numerous gradations which 

 bind together the most extreme forms into one whole. It may also 

 be observed that the gradual transitions presented by each group of 

 organs or each part have no correlations with those detected in 

 other parts of the organism. In the most widely separated species we 

 find a similar structure of certain parts, which, on the other hand, are 

 very dissimilar in nearly alhed species. There is a sort of inter- 

 lacing of characters which only allows of the establishment of arti- 

 ficial sections, and justifies, it seems to us, the course followed by the 

 author. 



The only new genus, which he has named Constantia, is distin- 

 guished by the structure of its two pairs of antennae, which are 

 modified so as to form locomotive organs. Their flagella are desti- 

 tute of sensory organs, and furnished with two rows of long, rigid 

 settc, which give them a plumose appearance. There is no appen- 

 dicular flagellum. X)l the legs are long and slender, especially the 

 second pair of walking-feet (fourth pereiopoda) and the first pair of 

 jumping-feet. The only species belonging to the genus (C. Brankkii) 

 does not keep at the bottom like the Gammari ; it is pelagic, and, 

 like other surface Crustacea, has a completely transparent body, so 

 that it can only be perceived in the water in consequence of its black 

 eyes. In reading what the author says of it, it is impossible not to 

 think of Cystosoma Septum, another almost perfectly transparent 

 Amphipod, which leads a pelagic existence in the Atlantic and In- 

 dian Oceans. 



Notwithstanding the gradual modifications which they present in 

 their different organs, the Siberian species of the genus Gammainis 

 are sufficiently distinct from each other in their general characters ; 

 indeed a considerable number are remarkable for their forms, pro- 

 portions, or ornaments. Some comparatively gigantic species attain 

 a total length of from 118 to 120 millims. (nearly 5 inches) ; but 

 the small species are much more abundant, and there are even 

 dwarfish forms of which the total length does not exceed 7 or 8 

 millims. 



