128 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



cate, not incised and furcate as in setosum. In coloration this species 

 may be at once distinguished from those abo^'e described in ha\ing 

 the antennae dark, deep brown or blackish, throughout while the 

 legs are pale as in the other forms. In the type the collum is white 

 but this may not be normal. The dorsum otherwise colored as in 

 glabrwn. 



Length, about 10.5 mm. 



355. MiMOSOMA GRACiLE, sp. nov. 



Type.— M. C. Z. 5,014. Solomons: Wainoni Bay (W. M. Mann). 



This is like the two preceding species in being essentially smooth 

 and glabrous; but unlike those species the transverse sulcus of the 

 tergites is deeply impressed and pronounced nearly to the keels. The 

 keels are small though sharply set off; angles of most not at all pro- 

 duced, a few posterior ones showing short spinous points as in the 

 preceding species; typically they show on the lateral edge two or 

 three minute and widely separated denticles or points. Anal tergite 

 rather strongly narrowed caudad, truncate at end. The dorsum is 

 solid black. Like M. setosum the first two antennal articles are light 

 colored but at other end only the seventh article instead of both sixth 

 and seventh is white, the intervening articles black. Legs white. A 

 very slender species. 



Length, near 10.5 mm. 



SoMETHUS, gen. nov. 



Body having the general form of Strongylosoma; cylindrical, 

 with the keels reduced, the second one below level of the others. 

 Composed of head and twenty segments. 



Antennae long and slender. 



Sternites without processes excepting the usual plate on the fifth 

 segment of the male. 



Pleural keels present only on second and third segments in the geno- 

 type. A process ectad of the base of each anterior leg on each seg- 

 ment, a more obscure one opposite the caudal leg. Pores on segments 

 V, VII, IX, X, XII, XIII, XV-XIX. 



Characterized by the structure of the male gonopods. In these the- 

 telopodite gives rise near its base on the mesal side to a spur or blade; 

 at the distal end it is bipartite, there being in the type also a short 



