244 M. A. Humbert on Niphargus puteanus, var. Forelii. 



that the most divergent opinions are still entertained as to the 

 value of the diiicrcnt specific and generic forms. 



The Niphnrgi observed by Caspary, Hosius, and De la 

 Yalette-St.-George were described under the name of Gam- 

 marus jmteayius, invented by C. L. Koch. Schiodte dis- 

 tinguished two other species in his genus Niphargus^ which 

 also includes this Gammarus puteanus. One of these, ob- 

 tained from the Austrian caverns, is his N. stygius ; the second, 

 found in a well in England, is his N. aquihx. tjpence Bate 

 has introduced two new species under the names of N. fon- 

 tanus and N. KocJn'anus. Costa has described a Gammarus 

 longicaudatus. Joseph has indicated a new species from 

 the caverns of Carniola under the name of G. orcinus. 

 Czerniavski has described a Niphargus ponticus from the Black 

 Sea. Lastly, we must also refer to an old species described 

 by Leach under the name of Gammarus suhterraneus. The 

 genus Eriopis, established for a marine species {E. elongatus) 

 found off the shores of Scandinavia at a depth of from 40 to 

 60 fathoms, seems to be synonymous with Nip>hargus. Finally 

 we have to mention a very nearly allied but easily distin- 

 guishable generic group, the genus Crangonyx, Sp. Bate, the 

 only known species of which {C. suhterraneus) has been found 

 in a well in England. 



According to M. de Rougemont*, to whom we are indebted 

 for the latest w^ork published on this subject, a great part of 

 these specific and generic names ought to disappear, as they 

 apply only to different forms simply representing the suc- 

 cessive stages of development of a single species. Among 

 the specimens collected by him in a well at Munich, M. de 

 Rougemont has found five distinct forms, which, however, are 

 transformed one into the other. The first, which is from 2 to 

 4 millims. in length, corresponds with Crangonyx suhter- 

 raneus^ Sp. Bate, and Gammarus pulex oninutus of Gervais. 

 The second, varying between 3 and 6 millims., is the N. Kochi- 

 anus, Sp. Bate. The third, measuring from 5 to 8 millims., is 

 referred to the Gammarus puteanus of Caspary and Hosius. 

 The fourth (12-14 millims.) is assimilated to t\\& N. fontanusj 

 Sp. Batef. The fifth (12-18 millims.) is determined as the 



* Philippe de Rougemont, ' Xaturgescliichte yon Ganunarus jmteanus, 

 Koch.' Inauguraldiss., 8vo, pp. 40, Munich, 1875. More recently M. de 

 Eougemont has published in French, under the title of ' Etude sur la 

 Faune des eaux privees de lumiere ' (4to, -with o plates:, Paris, 1870), a 

 memoir, which contains a translation of that above cited, together with 

 a description of Asellus Sieboldii and observations on a Hydrohia found in 

 a well at Munich. 



t We reproduce this synonymy with great reserve, because there are 

 contradictions between M. de Eougemont's text (p. 23j and his table of 

 species (p. 29) with regard to the third and fourth forms. 



