Boone, Crustacea, Cruise of ^'Alva," 1931 41 



preorbital. The entire fronto-orbital region is finely hirsute, as is 

 also the under frontal region. On the dorsal surface behind the hir- 

 sute area, the narrowed portion of the carapace is naked, smooth, 

 for quite a distance, behind this the convex surface of the carapace 

 is decorated with scattered, microscopic, pearly granules which are 

 larger and more abundant along the margins and adjacent regions 

 and on the three posterior spines. Immediately behind the tip of the 

 front, the anterolateral region of the carapace is formed of the ob- 

 liquely facetted sidewall of the subhepatic region, both the upper and 

 lower margins of the facet being beaded lines, on each of which near 

 the posterior end is a tubercle; the surface of the hepatic facet is 

 smooth. Posterior to the hepatic facet and situated between it and 

 the branchial region is a distinctly defined notch, coincident with a 

 depression on the pterygostomian face, which is continuous with a 

 well defined longitudinal groove, situated along the sidewall of the 

 carapace just above the slightly thickened epimeral margin. Behind 

 this notch the lateral border of the carapace is marked by a line of 

 finely beaded granules, which, in young specimens, are said to be occa- 

 sionally dentiform. On the posterior region of the carapace there is 

 a strong conical, outward and slightly upward directed spine in the me- 

 dian line, and outside it on either side there is a blunt, triangular tooth 

 which points outwards and slightly downwards. Each of these outer 

 spines is as wide at the base as its median length, which length is only 

 equal to two-fifths of the length of the median spine. These three 

 spines form an obtuse angle ; the median spine is not very high above 

 the other two. The sternal plastron is wide, smooth. The male belt 

 is narrow, triangular, with the first and second segments short and 

 wide, hinge-like; the third, fourth, fifth and sixth segments are com- 

 pletely fused, with a terminal granule. The seventh segment is a long 

 narrowed triangle with rounded tip. The female belt is wide, oval. 



The eye is small, brown, closely surrounded by the orbital margin. 



The antennulae are well developed and fold horizontally within 

 the fossett beneath the frontal border. 



The antennae are greatly reduced and are situated in the infra- 

 orbital sinus. 



The external maxillipeds are long, close-fitting, with the distal half 

 setigerous. The exognath has its ischium quite strong and small, its 

 merus as long as the total length of the endognath, with its outer mar- 

 gin widely rounded on the proximal two-thirds, narrowed distally 

 with its distal margin rounded; the endognath has its ischium com- 



