REPORT ON THE CRUSTACEA MACRURA. 437 



" The ophthalrnus not very distinct from the pedicle, the breadth scarcely equalling half 

 the length of the ophthalniopod, but certainly more than a third. 



" The first pair of antennae has the peduncle scarcely half the length of the carapace ; 

 the first joint subclavate and distinctly longer than the second and third. 



"The second pair of antennae having the last joint of the peduncle very short, robust, 

 subquadrate, nearly equalling in length one-fifth of the sublinear scaphocerite. 



" Sixth somite of the pleon scarcely longer than broad, and in length nearly one-seventh 

 of the animal ; shorter than the fourth and fifth somites united, and also than the united 

 lengths of the first and second ; nearly a third longer than the telson. 



'■ Pleopoda very short and stout. 



" Ehipidura having the outer branch armed on the external margin near the extremity 

 with a small point. 



"Habitat. — Greenland " (Kroyer). 



Sergestes dissimilis, n. sp. 



Animal slender. Carapace about one-third the length of the entire animal. Rostrum 

 slender, armed on the dorsal crest, slightly posterior to the frontal margin, with a small 

 tooth, and on the gastric region with a small dorsal cusp. 



Pleon having the five anterior somites subequal in length, the sixth being longer than 

 the preceding two united. The anterior three are dorsally smooth, the posterior three 

 being furnished with a small tooth at the posterior margin. 



Telson long and tapering, not reaching quite as far as the extremity of the inner 

 plates of the rhipidura, but nearly equal with the lateral tooth on the margin of the 

 outer plate, terminating in two strong teeth, and laterally furnished with two small 

 spines on each side. 



The ophthalmopoda are about one-third the length of the carapace, and reach a 

 little beyond the distal extremity of the first joint of the peduncle of the first pair of 

 antennae; they are clavate, gradually increasing in size from the base to the extremity, 

 where the ophthalrnus is of greater but not of suddenly increased diameter. 



The first pair of antennae has the first joint subequal in length to the ophthalmopoda, 

 and the two succeeding joints are subequal in length to each other, and together about 

 as long as the first. The flagella are broken, but judging from the portions left, the 

 smaller is longer than usual. 



The second pair of antennae carries a narrow scaphocerite that reaches beyond the 

 distal extremity of the second joint of the first pair of antennae, and terminates in a 

 rounded extremity, armed on the outer margin with a strong tooth. 



The gnathopoda and pereiopoda offer no very decided features of specific variation. 

 The second pair of gnathopoda is wanting, and the first pair of pereiopoda is broken off 



