356 DR. ^Y. T. CALMAN OX NEW OR RARE 



three-fourths as long as the distal segments together ; the distal segments are broad, 

 the carpus is distinctly longer than the merus, and the dactylus is twice as long as the 

 propodus. 



The remaining legs do not differ greatly in length ; the last pair are about one-third 

 of the total length of the body. The basis is a little over one-fourth of the length of 

 the limb, the carpus is' a little more than twice as long as the merus and about equal 

 to the propodus. 



The uropods have the peduncle a little over three-fourths as long as the last somite, 

 with two small teeth on the inner edge. The endopod is nearly three times as long as 

 the peduncle, with a stout terminal spine of about one-third of its length and with five 

 small spines on its inner edge. The exopod is less than one-eighth as long as the 

 endopod, with a slender terminal spine which does not reach to the end of the latter, 



jRemarks. — The specimens described above resemble the female of Sars's N. suhmii 

 even more closely than does that of I\. zimmeri, especially in the inflated branchial 

 regions and the posterior gibbosity of the carapace. They differ from N. siilimii in the 

 shorter and more obtuse pseudorostrum, in the less prominent dorso-lateral teeth of 

 the first abdominal somite and their absence from the following somites, in the 

 shorter carpus of the posterior legs, and in the much longer exopod of the uropods. 



Occurrence. — Gulf of Siam, " Koh Chang, about 1 fathom, coral," " Koh Kam, 

 5 fathoms, mud." Th. Mortensen Coll., Copenhagen Museum. Co-types in British 

 Museum. 



Naxnastacus eeptans, sp. n. (Plate XXXIII. figs. 22-28.) 



Description of adult Female. — Total length 1"5 mm. 



Carapace more than one-third of total length, little broader than deep. The 

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

 line below the respiratory orifice. The antero-lateral margin is deeply concave, the 

 antero-lateral corner produced and triangular. The eyes are prominent and darkly 

 pigmented. The surface of the carapace is very uneven, being depressed in the middle 

 line between the inflated branchial regions and with a median convexity anteriorly. 

 A few long setae are set on the branchial regions and on other parts of the surface. 



The first leg-bearing somite appears to be represented only by the pleural plates. 

 The remaining thoracic somites have the pleural plates expanded and rounded, without 

 spines. The last thoracic and the first abdominal somites have each, on the dorsal 

 surface, a pair of small spiniform teeth. 



The abdomen is nearly equal to the cephalothoracic region ; the fifth somite is a 

 little less than twice as long as deep and about one-third longer than the preceding 

 somite. 



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



