238 Prof. Dr. Fr. Yojaovsky on 



Although in the course of thirty years I have investi- 

 gated from this point of view hundreds of examples of the 

 species mentioned, I have not been able to find anything of 

 the ))igmcnt in question in a single individual, and I believe 

 therefore that we are driven to the conclusion that Leydig 

 only had Crangonyx before him. In this genus I have in- 

 variably found, not only in examples from Radotin, near 

 Prague, but also recently among great numbers of individuals 

 from the wells of Podbaba, near Prague, pigment-flecks on 

 both sides of the head, consisting of large branched cells such 

 as I have described in an earlier paper. 



Very interesting is the further statement of Moniez (14), 

 from which it appears that he observed a ^^ Gammarus jluvia- 

 tiiis^^ in the drinking-water of Emmerin, near Lille, whose 

 eyes appeared in the form of dark flecks. 



They were not so compact as in the normal freshwater 

 shrimps, but appeared to consist of single oraraatidia sur- 

 rounded by black pigment, and the crystalline cones were not 

 so round as in the typical species. Moniez therefore described 

 the form he had observed as G.Jluviatilis, var. d^ Emmerin. 

 According to the description we siiould have here a case of 

 rudimentary eyes exactly corresponding to what we have 

 specially described in Batliyonyx, and it is to be hoped that 

 the Emmerin variety may be subjected to an examination as 

 to its other characters in order to see whether it may not 

 represent a distinct species closely allied to Bathyonyx 

 de Vismesi. 



Not less important is the communication of R. Schneider 

 (19) about the Gammarus pidex living in the underground 

 waters of Claustal, in which the author found the eyes to be 

 in a peculiar condition. They are of irregular form, without 

 definite outline, with a little blackish pigment which is con- 

 fined to the centre of the eye, disappearing towards the 

 periphery. The crystalline cones are separated from one 

 another, and the eye is therefore diffusely formed as in our 

 Bathyonyx. R. Schneider designates the form as G. pulexj 

 var. suhterraneus ^. 



According to Garbini, the G. JluviatiUs observed by hira 

 near Verona exhibits the same arrangement with regard to 

 the eyes as Schneider's G. pulex^ and he calls the form 

 G.jiuviatilis, var. monopldhalmus. The same author mentions 

 also xV. eleyans, var. imperfectuSj with small brownish pigment- 



* [The original description by Schueider is given by Prof. Vejdovsky 

 in a long footnote, but it has not been thought necessary to reproduce it 

 in this translation. — Translator's note.'] 



