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



" Second pair of antennae having the scaphocerite linear, reaching a little beyond the 

 extremity of the peduncle of the first pair of antennae, eight times as long as broad, and 

 nearly nine times longer than the last joint of the peduncle. 



" Sixth somite of the pleon considerably elongated, sublinear, exceeding one-fifth of 

 the entire length of the animal, longer than the three preceding somites together, and 

 three times as long as broad. 



" Pleopoda very slender. 



" Telson but little shorter than the outer plates of the rhipidura, the outer margin of 

 which is furnished with a sharp tooth, situated not far from the distal extremity. 



" Habitat. — Greenland " (Kroyer). 



Sergestes arcticus, Kroyer. 



Sergestes arcticus, Kroyer, Monograph. Fremstilling af Kraeb. Sergestes, pp. 24, 60, Tab. iii. 

 fig. 7, a-g; Tab. v. fig. 16. 



" Rostrum rudimentary. 



" Ophthalmopoda pyriform, much shorter than the first joint of the peduncle of the 

 first pair of antennae ; ophthalmus very distinct from the pedicle, broader than long, the 

 diameter being equal to half the length of the ophthalmopod. 



" The peduncle of the first pair of antennae about one-third shorter than the carapace. 

 The second and third joints nearly equal in length, and together but little longer than 

 the first. 



" The last joint of the peduncle of the second pair of antennae three times as long as 

 broad, and about the third of the length of the scaphocerite. 



" Sixth somite of the pleon about the fifth part of the length of the animal, and 

 equalling that of the first, second, and third somites combined, but surpassing in length 

 that of the fourth and fifth somites combined ; twice as long as broad, and nearly twice 

 as long as the telson. 



" Pleopoda long and slender ; the basal joint of the fifth pair twice as long as broad. 



" The outer branch of the rhipidura armed with a tooth on the outer margin, one-third 

 from the terminal apex. 



" Habitat. — Greenland " (Kroyer). 



Sergestes obesus, Kroyer. 



Sergestes obesus, Kroyer, Monograph. Fremstilling af Krasb. Sergestes, pp. 41, 62, Tab. iv. 

 fig. 10, a-/. 



" Eostrum upright, rudimentary. 



" Ophthalmopoda pyriform, scarcely reaching to the extremity of the peduncle of the 

 first pair of antennae, but quite to the extremity of the second. 



