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



that the most divergent opinions are still entertained as to the 

 value of the different specific and generic forms. 



The Ni'pliargi observed by Caspar j, Hosius, and De la 

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

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

 tinguished two other species in his genus N^iphargus, which 

 also includes this Gammarus 'puieanus. One of these, ob- 

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

 found in a well in England, is his N. aquilex. Spence Bate 

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

 tanus and N. Kochianus. 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 Ni])hargus ponticus from the Black 

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

 by Leach under the name of Gammarus siibterraneus. 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 Niphargus. 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 ((7. subterraneus) has been found 

 in a well in England. 



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

 for the latest work 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 Grangonyx subter- 

 raneus, Sp. Bate, and Gammarus p>ulex minutus 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 the N.fontanus, 

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



* Philippe de Rougemoiit, ' Naturgeschichte von Gammarus puteanus, 

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

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

 Faune des eaux privees de lumiere ' (4to, with 5 plates, Paris, 1876), a 

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

 a description of Aselhis Sieholdii and observations on a Hydrohia found in 

 a well at Munich. 



t We reproduce this synonymy with great resei've, because there are 

 contradictions between M. de JRougemont's text ( p. 23) and his table of 

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



