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



the sixth somite, which is nearly as long as the three preceding somites combined. The 

 infero-lateral distal angle of each is rounded. 1 



Telson short, about one-third the length of the last somite. 



The ophthalmopod is about three-fourths the length of the carapace ; the ophthalmus 

 much larger than the diameter of the stalk. 



First pair of antennae with the peduncle longer than the ophthalmopod ; first joint 

 largely developed at the base to receive the otocyst ; the second and third joints nearly 

 as long as the first. 



The second pair of antennas carries a scaphocerite that is longer than the peduncle of 

 the first pair, narrow, with parallel margins, and armed on the outer or smooth margin 

 with a long tooth, somewhat distant from the apex. 



The first pair of gnathopoda is the only one preserved of the long appendages of the 

 pereion. 



The pleopoda are long and slender, and the terminal or sixth pair is armed on the 

 outer margin with a tooth that is nearly a third distant from the basal joint. 



Length, 5 mm. (0"2 in.). 



Habitat, — Pacific Ocean, lat. 24° 8., long. 148° W. 



Observations. — This specimen bears a close resemblance to the Challenger specimen 

 of Sergestes rinkii, which was also taken in the Pacific, but it differs in having the telson 

 shorter, the tooth on the outer margin of the rhipidura nearer the base, and in having a 

 strong tooth on the frontal margin of the carapace. It also differs from Kroyer's figure 

 of Sergestes rinkii in having a longer rostrum, and in the form of the scaphocerite ; 

 in both these points it corresponds more with our figure of Sergestes rinkii than with 

 Kroyer's. It differs from Sergestes penerinkii in having a frontal tooth at the outer 

 canthus of the orbital notch, in not having any tooth or protuberance on the ventral 

 median line of the somites of the pleon ; and in the shorter telson. 



Sergestes tenuiremis, Kroyer. 



Sei-gestes tenuiremis, Kroyer, Monograph. Frernstilling af KraVb. Sergestes, pp. 39, 62, Tab. iv. 

 fig. 11, a-6. 



" Eostrum upright, rudimentary. 



" Ophthalmopoda clavate, rather longer than the first joint of the peduncle of the first 

 pair of antennae, or at least equal to it ; the pedicle slender, elongated, distinct from the 

 ophthalmus, and more than twice as long. Ophthalmus nearly four times as broad as 

 long, one-third the length of the pedicle, and in diameter scarcely less than a third. 



" First pair of antennae with the peduncle only a little longer than half the length of 



1 I have unfortunately drawn an extra somite to the pleon ; there are only two smooth somites instead of three; 

 the second should have been omitted. 



