Boone, Crustacea, Cruises of "Eagle" and " Ara," 1921-28 57 



Technical description: Carapace rectangular, three-fourths as 

 wide as long, produced to an upcurved, attenuated, acute rostral 

 spine, which is three-fifths as long as the carapace, with the upper 

 surface paved with squamous rugae; the inferior lateral margins 

 carinate, these carinae continuous on the frontal margin; anterolat- 

 eral angles nearly right-angled, with an acute spine arising from the 

 tumid hepatic lobe; lateral margins subparallel; the precervical por- 

 tion of the carapace is circumscribed by the deep cervical groove and 

 is tumid; there is a pair of submedian spinules behind the rostrum 

 on the anterior gastric region; between these is a brief longitudinal 

 ridge ; posterior to this is a single median spinule, the three spinules 

 outlining a triangle ; a short distance behind the single spine is a pair 

 of smaller submedian spinules on the precervical region; the post- 

 cervical region is nearly as long as the precervical ; there is a deep, 

 transverse depression in the urogastric region, above which the cara- 

 pace is carinated and armed with one forward-pointing median spine ; 

 the posterior margin is heavily carinated. The entire dorsal surface 

 of the carapace is roughened by broken, transverse granules, some of 

 which are coarser than others. 



The abdomen has the first segment rudimentary; the second and 

 third segments each have a conspicuous transverse carina anteriorly, 

 which is ornamented with an acute forward-pointing median spine, 

 in addition to the above-mentioned carinae ; the second and third seg- 

 ments each have a prominent transverse carina across the median 

 region just anterior to the posterior margin; the second segment has 

 the epimera widely triangular, while those of the third, fourth and 

 fifth segments are extremely narrow and attenuated, triangular; the 

 third segment has no spine and only one transverse carina on the 

 median region not far behind the anterior margin; the fourth and 

 fifth segments are smooth; the sixth segment is narrower than the 

 others, with its postlateral margins converging, its posterior margin 

 relatively straight ; the telson is small, shield-like, with oblique suture 

 lines ; the rhipidura have a stout peduncle, the outer blade slightly the 

 smaller, narrow proximally, broadly widened and rounded distally; 

 the inner blade is much wider than the outer, with its distal and inner 

 lateral margins very convex ; both blades are ciliated. 



The cornea is short-stalked, bulbous. 



The antennulae have the proximal joint large and armed with one 

 very long, acuminate, up- and outward pointing spine on the superior, 

 subdistal margin; just below this there is a large, two-forked spine, 



