50 BULLETIN OF THE 



forward, one behind the other, and of which the anterior is considerably the 

 larger, and in the space between these teeth and the gastric region there are 

 two or three irregular lines of minute acute tubercles. Back of the cervical 

 suture, the upper lateral carina is high, conspicuous, and marked by a line of 

 about six acute teeth directed slightly forward, and the depression between 

 these and the lateral carina is armed with minute spiniform tubercles obscurely 

 arranged in longitudinal lines. The middle lateral carina is distinct, armed in 

 front with a small bidentate tooth and back of this by a very few small and 

 irregular teeth. The lower lateral carina is distinct, with the edge slightly 

 crenulated but not dentate. Below the carina of the antennal region there is a 

 longitudinal rugose ridge, and below and back of this a similar ridge on the 

 lower part of the branchial region. The surface of the branchial region between 

 the carinse is roughened by many minute tubercles, the inferior margin is bor- 

 dered by a conspicuous carina as in the last species, and just above this at the 

 postero-lateral angle there is a conspicuous elongated tubercle. 



The eyes are a little larger than in the last species, but do not differ in other 

 respects. The peduncles of the antennulse are clothed with coarser hairs than 

 in the last species, and the distal segments are hairy above as well as on the 

 sides, but in other respects they do not differ. The antennal scale is a little 

 broader than in the last species and the tooth of the outer margin is more 

 prominent and nearly half-way from the base to the tip, but the peduncle and 

 flagellum do not differ. The distal segment of the external maxilliped is no 

 longer than the penultimate, and the spines upon these two segments are a 

 little more slender and the whole appendage a little shorter than in R. Agns- 

 sizii. The legs of the first pair are a little shorter as a whole, and the propodi 

 and dactyli are relatively shorter. The legs of the second pair are exactly as 

 in R. Agassizii except that they are shorter and have fewer segments in the 

 carpi, the right leg scarcely reaching the tip of the peduncle of the antenna, the 

 left a little shorter, while the right carpus has twenty-three segments and the left 

 twenty. The legs of the third pair are stouter than in R. Agassizii and only 

 reach to tips of the antennal scales, but the relative lengths of the segments are 

 about the same. The fourth and fifth pain are proportionally short and stout, 

 and the dactyli very different from those of R. Agassizii. These arc alike in 

 both pairs, about a fifth as long as the propodi, shorter than in the third pair, 

 not at all compressed but nearly cylindrical, even Blightly swollen distally, and 

 very abruptly contracted into a bifid tip, the inner tooth of which is the longer, 

 more acute, and curved. 



The form and sculpture of the abdomen is very similar to thai of the last 

 species, but the dorsal carina on the first somite is interrupted posteriorly and 

 on the second is not so high ; the teeth of the lateral carina on the first somite 

 are no t unite as acute ; the tubercles over the surface generally are more 

 ularly arranged, and none of them are much elongated ; the marginal spines of 

 the epimera are shorter and less curved, but the anterior tooth <>n tin- second 

 epimeron is much larger though obtuse ; the fifth is armed with three spiniform 

 teeth, a median tooth, and two smaller nearly equal lateral teeth; and the 



