182 Richardson Sphseromidw from Alaskan Waters. 



This genus differs from the genus Ancinus of Milne Edwards 



1. In having uropoda with two branches instead of one. 



2. In having the abdomen entire and not truncate at the tip. 



3. In the prominent projection of the anterior and lateral margins of 

 the head. 



4. In the concealment of the antennae, which are very conspicuous in 

 the Ancinus. 



Tecticeps alascensis sp. nov. 



Outline of body oval. Surface quite smooth, but covered with little 

 points of depression. 



Head large ; twice as long as any one of the thoracic segments. The 

 anterior margin is produced in a way to conceal the antennae, as are also 

 the antero-lateral margins, making the anterior portion of the head in 

 front of the eyes much broader than the posterior portion, and forming 

 very acute antero-lateral angles. This frontal margin forms a very broad 

 obtuse angle with its apex in the median line. On either side of this 

 apex to the antero-lateral angle this portion of the head is somewhat de 

 pressed. The antennae are not conspicuous*, lying concealed beneath the 

 frontal margin of the head. The first pair extends 

 to the posterior angle of the first thoracic segment ; 

 its flagellum contains ten articles. The second pair 

 reaches the middle of the second segment ; its flagel 

 lum is twelve-jointed. The eyes are dorsally situ 

 ated on the posterior half of the head. 

 Fig. io. , Antenna of rp ne ^ norac i c segments are about equal in length. 



of 2d aif air ' ^tfT The first One extends laterally around the posterior 

 portion of the head, forming a broad plate at the side 



of the segment. The epimera of all the segments are about twice as broad 

 as long, with the exception of those of the fifth segment, which are 

 nearly square and very conspicuous. 



The first segment of the abdomen has three suture lines, and its pos 

 terior margin projects down at the sides over the terminal segment. The 

 terminal segment is triangular, and has a very pointed 

 extremity. The uropods differ considerably. The in 

 ner one is broad and tapering, and does not reach the tip 

 of the abdomen. The outer one is slender and sharply 

 pointed, and extends beyond the abdomen. 



The first pair of legs are subchelate, as are also the 

 second pair. In the first pair the propodus is large and 

 oval in shape, and bears in the pahna a row of stiff FIG. n.-a, Mandi- 

 bristles at regular intervals and pointing obliquely in the 

 same direction, while a thick row of fine cilia, pointing 

 obliquely in the opposite direction, cross these almost at 

 right angles. The dactylus terminates in a single hook, at the base of 

 which two smaller hooks are situated. In the legs of the second pair the 

 propodus is irregular in shape with an indication of a rudimentary 



