CRUSTACEA CASl'IA. 199 



sjiecies of the geuiis Gammarus, there occurs iu tlie 2 posterior ones, on 

 each side of the dorsal face, a fascicle of small sjnimles. their number being 

 generally 2 in each fascicle. 



The cephalon is somewhat shorter than the first 2 segments of the meso- 

 some combined, and exhibits a rather irregular form. As seen laterally 

 (fig. 2) it rapidly tapers anteriorly, being narrowly truncated at the tip, 

 with the rostral projection extremely small and the lateral lobes narrowly 

 rounded in front. The inferior edges of the ce])halon between the latter and 

 the postantennal corners are nearly straight and obli(iuely descending, and just 

 above them issues from the lateral faces on each side a rather large umboni- 

 form prominence, best seen iu the dorsal view of the animal (conip. fig. 13). 



The coxal plates nearly agree in their shape with those iu the preceding 

 species, the 4 anterior pairs being rather large and considerably deeper 

 than the corresponding segments. The 5th pair (see fig. 7) are somewhat 

 oblique and much deeper in their anterior than posterior part. 



The epimeral plates of the metasome are well developed, the 1st pair 

 being, as usual, rounded, whereas the 2 succeeding pairs are nearly rect- 

 angular, with the lateral corners but slightly ])roduced. 



The eyes (see fig. 2), which are placed close to the extremity of the 

 cephalon, are of oval reniform shape and remarkable by being so highly 

 protuberant as nearly to exhibit a stalked appearance (comp. fig. 13). They 

 have the visual elements well developed and the pigment of a very dark hue. 



The superior autennga (see fig. 1) are comparatively short, scarcely ex- 

 ceeding in length % of the body, and are, as in the preceding species, but 

 sparingly setiferous. The 1st joint of the i)eduncle is but little longer than 

 the 2nd, and the 3rd only half the length of the latter. The flagellum does 

 not attain the length of the peduncle, and is composed of about 1 5 short 

 articulations. The accessory appendage (see fig. 3) is very small and exactly 

 of same appearance as iu the preceding species. 



The inferior antennte are about same length as the superior, and have 

 the penultimate joint of the peduncle the largest. The flagellum is scarcely 

 half as long as the peduncle and composed of 6 articulations. 



The gnathopoda (figs. 4 and 5) exhibit a structure very similar to that 

 in the preceding species, the posterior ones (fig. 5) being a little more 

 elongated than the anterior and having the carpus somewhat larger. The 

 propodos is in both pairs oblong oval in form, and but little broader than 

 the carpus, with the palm somewhat oblique, though not nearly as long as 

 the hind margin. 



The 2 anterior pairs of pereiopoda (fig. 6) do not difler in any way from 

 those in the preceding species, and also the posterior pairs (figs. 7 and 8) 



