232 I'rof. Dr. Fr. Vej.lovsky o« 



capsules are innervated from tlie cutaneous nerves, for a pale 

 but sharply contoured nerve-thread approaches the base of each 

 capsule and then clearly passes along the stalk to be joined 

 to the sensory seta. The nerve-fibre always originates from 

 one ganglion-cell, as is accuratel}^ shown by Haniann. 



The sensory capsules are found on all the segments. On 

 the ceplialic segment of Bathyonyx, close behind the diffuse 

 eye, there are 4-5 capsules arranged in a curved line 

 (fig. 17, sjoo), and not far behind there is a second row of 

 3-4 capsules (fig. 17, spo). On the following segments 

 the number may be less, but they occur more or less 

 regularly also on the hinder segments. 



in Crangonyx I alwaj's found, in the hinder region of the 

 body, four capsules on each segment, two anterior and two 

 posterior, while on the anterior segments they were rarer and 

 less regularly distributed, although one must take into account 

 the circumstance that the structures can easily escape 

 observation by reason of their minuteness and their usually 

 small refractive power. 



The attention of earlier investigators was very often given 

 to the sensory capsules. Thus La Valette observed them on 

 the back and therefore referred to them as " capilliin corporis 

 dorso siti." Humbert recognized them as sense-organs and 

 designated them accurately as " capsules sensitives." As 

 Hamann justly remarks, Leydig combatted the correctness of 

 this expression, " for it is not a question of capsules but of 

 modified cuticular canals. But from his description it is 

 evident that he classed these organs with the similarly formed 

 hair-structures of the antennse and only examined the latter." 

 Vom Rath and more recently Hamann have correctly described 

 and figured the sensory capsules (referred to by Hamann 

 as sensory clubs). Delia Valle calls the organs " peli," but 

 Lis figures are reproduced on a small scale, so that the 

 structure of the capsules, nerve-endings, and sensory setas do 

 not clearly appear. 



The most remarkable organs of Bathyonyx are undoubtedly 

 the EYES, and for this reason I propose to describe them in 

 detail. Not one of the four above-mentioned specimens has 

 normal compound eyes such as are found in Gammarus^ but 

 visual organs with scattered components on both sides of the 

 head. Unfortunately, owing to the fixing agent, the pig- 

 ment was not perfectly preserved, so that it is impossible to 

 state exactly the number of the pigment-cells. 



One example was cut into a complete set of serial sections, 

 principally with the object of showing more precisely the 

 relation of the nerves and optic ganglia to the external visual 



