244 Oil some FresJnvater Ainphlpods. 



Fiy. 19. Section through the diffuse eye of a specimen preserved in formol- 

 Tiie cLitide (c) is widely separated from the hypodermis {hp)- 

 7-t, retinula. 



Figs. 20-30. Segmental sensory capsules of difierent representatives of 

 the genera Gammarus, Niphargus, and Crangonyx. 



Fig. 20. Gammarus sp., from Herzegovina (22 ju, long). 



Fig. 21 a, b. Gammarus from Lautenthal (16 jx). 



Fig. 22. Niphargus elegans from Modena. 



Figs. 23, 24. Niphargus puteanus from Prague (12 /n). 



Fig. 25. Crangonyx compactus. 



Fig. 26. Niphargus tatrensis (Switzerland). 



Fig. 27. Niphargus from Lille. 



Fig. 28. Niphargus Caspary from Munich. 



Fig. 29. Niphargus Kochianus from Lough Mask ; b, in optical section. 



Fig. 30. Crangonyx subterraneus from Podbaba, near Prague. 



[The foregoing paper bj Prof. Vejdovsky, of Prague, lias 

 been translated by my friend Mr. D. J. Scourfield, and would 

 have appeared in print last year, but that it seemed desirable 

 if possible to supplement the information by the result of 

 further researches. Unfortunately three days' dredging 

 undertaken last summer, and again this year, failed in 

 securing any additional specimens of Bathyonyx de Vismesi, 

 although 251 examples of Niphargus Kochianus^ Bate, were 

 taken in Lough Mask. The bright orange colour which 

 characterizes them all, as well as Bathyonyx., from the lake, 

 finds a parallel in the observation of ^I. Ohevreux referring 

 to Niphargus Plateaui, var. robustus, captured in an open 

 basin formed by the source of the Robine at the foot of the 

 mountains of Gardiole, the adult specimens of which he 

 described to be of a salmon-red, paler in the younger indi- 

 viduals. The probability that these animals might have 

 been originally introduced from the underground streams that 

 percolate the limestone strata about Lough Mask suggested 

 an investigation of these latter. Accordingly, Lord Ardilaun's 

 permission having been given, a research was conducted into 

 the subterranean waters in his extensive grounds near Cong. 

 This resulted in the discovery of thirteen N. Kochianus in 

 one cave and a single specimen in another. All fourteen 

 were of the usual translucent hue which I am accustomed to 

 see in examples of Niphargus taken from wells, but, with 

 the exception of their colour, were in every respect identical 

 with those of the lake. Hence it is now scarcely open to 

 doubt that the blind species of Niphargus recorded as occurring 

 in Lough Mask, the Lake of Geneva, the Lake of Zirknitz in 

 Carniola, and some Swiss lakes, have been derived from their 

 congeners inhabiting subterranean waters, and that the orange 

 or salmon-red colour of those in Lough Mask and those cited 



