MUSEUM OF COMPARATIVE ZOOLOGY. 87 



Amalopenseus elegans, sp. nor. 



Plate XIV. Figs. 8-14. Plate XV. Figs. 1-5. 



The carapax is not at all compressed laterally, but about as broad as high, 

 exceedingly thin and membranaceous, and its surface naked and polished. 

 The branchiostegial spine is very minute and the carina which extends back 

 from it is less conspicuous than the sharp gastro-antennal and gastro-hepatic 

 carina which is continuous posteriorly with a distinct cardiaco- branchial one ; be- 

 tween the gastro-antennal and the branchiostegial carinse there is a wide anten- 

 nal and hepatic sulcus, which posteriorly turns down in front of the branchial 

 region ; there is a slight gastro-frontal and a very conspicuous transverse gastric 

 and gastro-hepatic sulcus, as in the last species, while the cervical itself is equally 

 deep and conspicuous, notches the dorsum like the gastric and only a very little 

 way back of it, is directed downward and backward and then in a regular 

 curve forward round the hepatic region to join the hepatic sulcus. A sharp 

 dorsal carina extends the whole length of the carapax, but is most conspicuous 

 in front of the gastric sulcus, rises in front into a sharp lamellar crest armed 

 with a single sharp tooth over the posterior margin of the orbit, and projects 

 forward in a short but acute and laterally compressed rostrum, which scarcely 

 reaches the middle of the eyestalks. 



The eyes and eyestalks are very nearly as in the last species, but the denti- 

 form prominence is very much more prominent and conspicuous ; the color of 

 the eye and position of the pigment spot are the same, though the latter is 

 more conspicuous above than below. 



The ultimate segment of the peduncle of the antennula is much longer than 

 the penultimate, and these two taken together are nearly as long as the first 

 segment, but in other respects the peduncle is as in the last species. In the 

 male the flagella are proximally subequal in diameter, but the superior is ex- 

 panded somewhat along the inner side for a short distance from the base. 



The antennal scale (PI. XIV. fig. 12) is much less than half as long as the 

 carapax, nearly three times as long as the greatest breadth, which is near the 

 base, from where the margins arcuately converge to a narrow but obtusely 

 rounded tip, which is scarcely in advance of the small terminal spine of the 

 outer margin. The rest of the antennal peduncle is nearly as in the last species, 

 and is armed with a curved spine above the base of the scale in the same way, 

 but the terminal segment is shorter to correspond with the shorter scale. The 

 flagellum is nearly naked, very slender, and at least much longer than the rest 

 of the animal. 



The labrum, metastome, and crowns of the mandibles are nearly as in the 

 last species, but the labrum is full and rounded below. The mandibular palpi 

 (PI. XIV. fig. 9) are very large, and reach nearly to the middle of the antennal 

 scales : the proximal segment is more than half as broad as long, nearly twice 

 as long as the distal segment, with the distal part of the mesial edge straight 

 and the outer edge curved and directed inward distally so as to narrow the 



