1'22 CARCINOLOQICAL STUDIES. 



40. Hetairocaris orientalis , n. sp. 

 (PI. 6, fig. 16). 



Two ova-bearing females from the island of Ponape. 



This species much resembles in its outer appearance 

 Hippolyte brevirostris Dana from the West-coast of North 

 America. The cephalothorax is rounded above and smooth. 

 The short , slender rostrum is laterally compressed and 

 arises with a carina from the anterior fifth part of the 

 cephalothorax ; it is directed horizontally forward and does 

 not reach to the distal end of the first joint of the peduncle 

 of the inner antennae. The upper margin is armed with 

 four acute equal teeth, placed on equal distances ; 

 the two posterior teeth are placed on the cephalothorax, 

 the two anterior on the rostrum itself. The lower margin 

 is straight and entire. On each side of the second tooth 

 of the rostrum the supraorbital tooth is placed; these supra- 

 orbital teeth are about twice as large as the teeth of the 

 rostrum ; they do not reach to the extremity of the third tooth 

 of the rostrum in the larger specimen , whereas they reach 

 to it in the smaller one. The antennal tooth is small , and only 

 half as long as the supra-orbital one ; there is no second an- 

 tennal tooth, and the fronto-lateral angle is rounded. 



In both specimens the abdomen is deflexed towards the 

 ventral side. The lateral margins of the antepenultimate 

 segment terminate in an acute tooth , and the posterior 

 margin presents a second tooth which is smaller and less 

 acute , on each side of the middle line , close to the 

 lateral teeth. The penultimate segment is but little 

 longer than the antepenultimate; the lateral margins 

 terminate in an acute tooth and the posterior margin pre- 

 sents two other teeth which are as acute as the lateral. In 

 the species of the genus Hetairus figured by Spence Bate, 

 this segment, on the contrary, is considerably longer than 

 the antepenultimate one. All the postabdominal segments are 

 rounded above and smooth, except the telson. The telson 



Notes from tlae Leyden Mixseuiin , Vol. X-Il. 



