Boone, Crustacea, Cruise of "Alva," 1931 85 



(Balss) ; Bagan, Api Api, Sumatra (de Man) ; Durian Straits 

 (Boone). 



Material examined : Two small females, taken in 14 fathoms, 

 muddy bottom, near Equator, to the southward of South Broth- 

 er's Island, south entrance of Durian Straits, Lat. 29' N. by E., 

 Long. 104° 47' E. 



Technical description : The larger female is about 20 milli- 

 meters long. The carapace is 5.6 millimeters long from the apex of 

 rostrum to the posterior margin, the rostrum being 1.2 millimeters 

 long from apex to orbital angle. The rostrum arises as a laminate 

 carina, about 1 millimeter posterior to the frontal margin, and is 

 continued forward and obliquely upward for a distance of not 

 quite one-third of the carapace length, or almost to the distal mar- 

 gin of the cornea. There is no epigastric spine present in either of 

 the two females, but these are both very young. The upper margin 

 of the rostrum is a smooth carina on the proximal two-fifths or 

 postorbital portion, while the distal portion beyond the carapace 

 is serrated by five acute, closely spaced teeth, in addition to the 

 apex. The inferior rostral margin is produced into a thin, shal- 

 low lamina, which is slightly convex on the ventral margin and 

 finely ciliated. The base of this lamina is defined from the rostrum 

 by the lateral carina, which is continuous posteriorly with the 

 orbital margin. The carapace is elongate, microscopically setiger- 

 ous, punctate, possessing an acute postorbital tooth, also a strong, 

 acute, hepatic tooth which is set well back upon the hepatic area. 

 There is a strong sulcus above the hepatic spine, extending from 

 immediately below this spine, obliquely up and backward for two- 

 fifths of the distance to the hind margin ; the upper end of this 

 sulcus approaches but does not reach the median dorsal line. 

 The subhepatic sulcus is contiguous with the superior sulcus at 

 their point of origin beneath the spine, and extends obliquely 

 downward for a short distance. The preorbital angle is an acute 

 spine. The anterolateral angle is an acute triangle, smaller than 

 the postorbital angle. The abdominal segments are characteristic 

 of the genus, the anterior three segments being dorsally rounded, 

 while the fourth, fifth and sixth segments are sharply carinated 

 in the median line ; the fifth segment terminates in a minute den- 

 ticle posteriorly ; the sixth segment is greatly elongated, two and 

 a fifth times as long as the fifth segment, or subequal in length to 

 the short, triangulate telson. The latter is quite narrow proxi- 



