REPORT ON THE ISOPODA. 41 



The first segment is much longer than either of the two succeeding segments ; at the 

 lateral margin are three long spines of which the anterior is the longest and bears two 

 short branches at its base ; the dorsal surface of this segment, as of the body generally, 

 is roughened and tubercular ; on the median lateral regions of the dorsal surface are a 

 few spines, of which one on each side is particularly long. The two succeeding segments 

 of the thorax are subequal ; on the lateral margin are two spines, of which the anterior is 

 the longer ; there are also a few stoutish spines upon the dorsal surface of these segments. 

 The fourth segment is longer, and as usual in this genus broader anteriorly than 

 posteriorly, where it comes into contact with the following segment ; it has a few short 

 spines, but no long lateral spines like those of the preceding segments. The fifth segment 

 of the thorax is as usual the longest and somewhat f-shaped, the arms of the T being at 

 the hinder end of the segment where the limbs are articulated. Along the latero-dorsal 

 regions of this segment, in the anterior cylindrical section, are a row of about seven short, 

 stout spines on either side of the body. The epimera of this segment, as of the two 

 following, are visible on a dorsal view ; they are short, rounded, and tuberculate, like 

 the rest of the body surface. The sixth and seventh segments of the thorax are very 

 short with rounded margins, and like the preceding segment without any lateral 

 spines. 



The first segment of the abdomen is free from the abdominal shield ; it is of about 

 the same size as the last segment of the thorax, both being a trifle narrower than the 

 sixth thoracic segment ; along the lateral margins are a few short blunt spines. 



The abdominal shield has a rather peculiar shape, which is characteristic of the species ; 

 the anterior margins form an oval. There is a deep notch just in front of the articulation 

 of the uropoda which are borne upon a short truncated process ; the extremity of the 

 caudal shield is prolonged for some way behind the articulation of the uropoda, 

 and terminates abruptly in a straight margin. The dorsal surface has a median 

 and two lateral convexities ; the former is bordered by three short spines on either 

 side, and there are a few similar spines scattered over the lateral regions, one being 

 especially prominent just in front of the lateral notch which precedes the articulation of 

 the uropoda. 



The antennules are rather peculiar in shape (see fig. 2) ; they consist of a large stout 

 basal joint, with which is articulated an elongated second joint which is considerably 

 narrower, and bears a few long slender hairs upon the inner side ; the last of these is very 

 much longer than the rest ; at the summit of this is articulated an extremely minute three- 

 jointed flagellum. 



The antennai (fig. 3) appear to be shorter than the body, but as a portion of the flagellum 

 was broken off, their exact length cannot be given ; the proximal joint is very short, the 

 second long, and both these joints have a number of long, stout, rough spines ; the first 

 joint has two of these on the inner side ; the second joint has two rows, one on either side 



(ZOOL. CHALL. EXP. — PART XLVIII. — 1886.) Bbb 6 



