422 THE VOYAGE OF H.M.S. CHALLENGER. 



as long as the ophthalmopod, and supporting a scaphocerite that reaches beyond the 

 distal extremity of the second joint of the first pair of antennae ; the outer margin is 

 armed with a long, slender tooth, somewhat distant from the rounded apex, which is 

 fringed with a series of fine hairs. 



Oral apparatus situated halfway between the frontal and posterior margins of the 

 carapace. 



The mandible furnished with a long synaphipod. which does not reach to the frontal 

 margin of the carapace. 



The first pair of gnathopoda has the ischium and meros reaching but a little in front 

 of the oral apparatus, and the whole of the appendage when extended scarcely reaches 

 to the frontal margin of the carapace. 



The second pair of gnathopoda is missing, being broken off at the coxa, which is 

 broad and formed for carrying a powerful organ. 



The first pair of pereiopoda is short as compared with the second and third, but not 

 much shorter than the first pair of gnathopoda ; the ischium and meros are long and 

 robust, and the two terminal joints feeble and ciliated. The second and third pairs are 

 long, slender, fringed with long hairs, and terminate in minute but long, fringed chelae. 

 The fourth pair is about half the length of the preceding, and fringed with long hairs on 

 the posterior margin of the distal extremity. Fifth pair little more than half the length 

 of the fourth, very slender, and fringed with hairs. 



Pleopoda long and slender, gradually decreasing in length and increasing in breadth 

 posteriorly. 



Posterior pair having the outer branch nearly twice as long as the telson ; outer 

 margin straight and armed with a small tooth one-fourth distant from the extremity, 

 beyond which the margin is fringed with short hairs, as also are the inner margin and 

 both margins of the inner plate. 



Habitat. — South Atlantic Ocean, October 5, 1873 ; near Station 131 ; lat. 29° 35' S. 

 long. 28° 9' W. 



Length, 25 mm. (1 in.). 



Station 295, November 5, 1875 ; lat. 38° 7' S., long. 94° 4' W.; South Pacific Ocean ; 

 depth, 1500 fathoms; surface temperature, 52°'5. Taken at night. 



Length, 8 mm. (0"3 in.). 



Observations. — This species comes very near to Sergestes tenuiremis, Kroyer, but 

 differs from it in the form of the rostrum, which is represented in Kroyer's figure as 

 standing erect on the dorsal surface, but which in our specimen is reduced to a mere point 

 on the frontal margin. 



The specimen from the South Pacific is more pronounced than that from the South 

 Atlantic, and the ophthalmopod corresponds more nearly with Kroyer's species. 



