269 



and pubescent, but the granules are much smaller; this gastric region is not subdivided. On 

 the whole posterior third of the carapace the granules are largest and most crowded; cardiac 

 and branchial areas are not discernable. The surface is but little vaulted in longitudinal direction, 

 and nearly straight transversely. The whole animal is soft, the skin being membranaceous and 

 yielding to a slight pressure. 



Front finely granulate, with a transverse row of short hairs along anterior margin, 

 narrowing anteriorly, regularly deflexed ; anterior margin exactly twice as broad as either orbit, 

 straight in dorsal view, but in reality projecting in the median line and continued into a thin 

 nasal plate, separating the nearly transversely-folded antennules, lateral angles of the front 

 pronounced, bent downward. Fronto-orbital distance half the greatest width of carapace; orbits 

 small, well defined; eye-stalks short, thick, movable; eyes well developed, with black pigment. 

 Lateral margins of carapace regularly curved, obtuse; posterior margin of carapace little convex, 

 longer than fronto-orbital distance. 



Epistome very short, but distinct, strongly folded transversely. Antennae unusually long, 

 as long as width of front, the three free basal segments of the peduncle elongate, the terminal 

 one 1.5 times as long as the preceding; flagellum consisting of seven segments, the penultimate 

 one with one strong hair, the terminal segment with three such hairs. Pterygostomian regions 

 finely granulate, subhepatic and subbranchial regions with a dense and soft fur of feathered 

 hairs. Buccal cavity rectangular, with the anterior angles rounded, much wider than long. 

 External maxillipeds (fig. i a) very widely gaping, the gap being filled to a great extent by 

 the broadly-expanded palpi, margins thickly fringed with very long, silky, flexible, bearded 

 hairs. De Man already accurately described and figured these maxillipeds, but I should wish to 

 emphasize a few points: de Man states that the ischium, which is distinctly smaller than the 

 merus, is broader than long, but the contrary is shown in his figure, and the ischium in my 

 specimen is indeed broader than depicted by de Man, its outer surface is crossed by a transverse 

 row of feathered hairs; the merus is longer than the ischium, widening distally, with the inner 

 margin straight and fringed with very long hairs, the outer margin convex, likewise hairy, 

 the external surface of the merus is crossed by a distinct transverse row of feathered hairs 

 similar to those on the ischium, but the hairs are much longer^); the palp is extremely 

 bulky, more so than ischium and merus together, and the outer margins of carpus, propodus 

 and dactylus, which are placed end to end, are heavily fringed with very long, feathered 

 hairs, carpus and propodus are of subequal length, bent rectangularly to each other, the 

 former is subquSdrate, the latter broadly-triangular and its antero-external angle, which projects 

 freely, is provided with an additional tuft of dense hairs, the dactylus is of the shape of the 

 propodus, but somewhat shorter, much flattened, and the hairs fringing the external margin 

 are continued along the distal border, though keeping here the same transverse course and 

 not expanded fan-like. The close resemblance of these maxillipeds to those of the genus Thau- 

 mastoplax Miers strongly suggests a near affinity between the two genera, which view, of 

 course, is strengthened by the great reduction of the last part of legs in Tetrias. We must. 



l) It is this transverse row which seeins to be one of the generic characteristics, as it is also described and figured in 

 T. scabripcs Rathbun. 



121 

 SIBOGA-EXPEDITIE XXXIX t'. 35 



