22S Trof. Dr. Fr. Vejclovsky' on 



pio-nieiit, whicli in no way possess the cliaracters of the genus 

 Mphargut,; but are representatives of a new genus inter- 

 mediate between Crangonyx and Gammarus, which I 

 designate Batliyonyx. To the species I give the name of 

 B. de Vismesi, gen. nov., sp. n., in honour of the discoverer. 

 Generic and specific characters : — Bathyonyx ^vUh both 

 pairs of antennce very sli07't [the Jlagellum of the first iisudUi/ 

 ('i-jointed, that of the second A-jointed\ xoith "l-jolnted secondary 

 branch on the first antennae. Eyes consisting of crystalline 

 cones diffusely distributed in the pigment. Gnathopoda loith 

 iceahly developed hands ; the hands of the anterior gnathopods 

 broader than those of tlie second pair. Telson split for two- 

 thirds of its length, consequently hilohed. Third puir of uro- 

 ptods xcith an outer 2-joitited, and a short inkier \-jointed 

 branch, scantily furnished with seta^, as in Crangonyx. Seg- 

 mental capsular epidermal sensory organs fusiform. 



Bathyonyx de Vismesi, gen. et sp. nii. 



The fonr specimens examined were all of equal length, 

 namely 3 mm., and of similar form. Being preserved in 

 formol they still sliowed traces of the original pale orange- 

 red coloration which was especially noticed by de Vismes 

 Kane in the living condition. 



The anteunai are remarkably short, attaining about one- 

 fourth of the body-length ; there is no well-marked distinction 

 between the joints of the peduncle and the flagellum, for the 

 three basal joints pass gradually into those of the flagellum. 

 In this way the total number of joints of the first anteniipe 

 amounts to nine in two specimens and eight in the third. 

 (The fourth example was cut into serial sections.) The 

 third joint carries the 2-jointed secondary branch, of the 

 same form as in Niphargus for example, i. e. with an 

 elongated and greatly swollen basal joint, and a short and 

 slender distal joint (PI. XI. fig. 2, r?)- The antennal setie 

 are weak, short, and scanty, from 1-4 on each joint as in 

 Niphargus. The sensory seta3, which I have described from 

 the antennse of Crangonyx as sensory bruslies [Siiniespinsel], 

 are also jjresent in Bathyonyx, but they are very feebly 

 developed, so that they can be easily overlooked. 



These remarkable sense-hairs are characteristic not only of 

 these genera, but also of JViphargus and Gammarus (especially 

 those of the first joint of the first antennre), occurring, iu fact, 

 in the last-named genus in the greatest number. 



Thus in G. fi.uviaiilis from Herzegovina (collected by 

 Dr. Thon) 1 invariably found seven sensory brushes on the 



