CUMACEA FROM THE COPENHAGEN MUSEUM. 359 



Naxnastacus tardus, sp. n. (Plate XXXIV. figs. 4-11.) 



Description of adult Female. — Total length 1-6 mm. 



Carapace about three-sevenths of total length, considerably broader than deep. 

 The pseudorostrum is very short and truncate, and the two parts meet together in 

 the middle line below (and apparently also above) the respiratory orifice. The antero- 

 lateral margin is deeply concave, the antero-lateral corner produced and triangular, 

 extending in front of the pseudorostrum, the lower edge serrated anteriorly. The 

 surface of the carapace is not very uneven and the branchial regions are only slightly 

 iuHated. 



The first leg-bearing somite is represented only by the pleural plates, which, like 

 those of the following somites, are greatly expanded laterally and bear a marginal 

 row of laminar spines (partially detached in the specimen figured). The second leg- 

 bearing somite has a small median tooth dorsally. 



The abdomen is shorter than the cephalothoracic region : the first somite has a pair 

 of small dorso-lateral teeth, but these are often absent, or perhaps readily become 

 detached ; the fifth somite is at least twice as long as deep and nearly one-half longer 

 than the preceding somite. 



The antennule has the second and third segments of the peduncle subequal and 

 together about equal to the much stouter first segment. 



The third maxillipeds have no exopods. The basis is less than one-third of the 

 total length of the limb, and its distal process is very long and narrow. 



The first legs also have no exopods. The basis is about two-sevenths of the total 

 length of the limb, and has a prominent rounded lobe on its inner edge. 



The second legs are without exopods. The basis is about three-fourths as long as 

 the remaining segments together. The carpus is much longer than the merus and the 

 dactylus is not twice as long as the propodus. 



The remaining legs are subequal in length and less than one-third as long as the 

 body. The basis is about one-fourth of the length of the limb, the carpus is less thaa 

 three times as long as the merus and about equal to the propodus. 



The uropods have the peduncle little more than half as long as the last somite. 

 The endopod is a little more than twice as long as the peduncle, with a stout terminal 

 hj)ine of less than half its length and three small spines on the distal part of its inner 

 edge. The exopod is about one-sixth as long as the endopod, and its terminal spine 

 does not reach to the end of the latter. 



Remarks. — In the form of the carapace, with its strongly produced antero-lateral 

 angles and slightly inflated branchial regions, this species approaches more closely to 

 A. iingtn'ciilattis than to any other species hitherto described. It differs from that 

 species, however, in having no exopod on the third maxilliped, in the absence of 

 si)ines from the carapace and from the dorsal surface of the posterior abdominal 



3c2 



