REPORT ON THE CRUSTACEA MACRURA. 401 



Sergesttis armatus, Kroyer (PI. LXXIII. fig. 1). 



Sergestes armatus, Kroyer, Monograph. Frernstilling af Krajb. Sergestes, pp. 44, 63, Tab. iii. 

 fig. 6, a-e. 



" Rostrum distally prominent, acute, fully half the length of the ophthalmopod. 



" Ophthalmopoda long, reaching considerably beyond the second joint of the first pair 

 of antenna, broadly clavate or subfungiform, ophthalmus very distinct from and nearly 

 as wide as half the length of the ophthalmopod, and as long as one-third of it. 



"First pair of antenme having the peduncle one-half the length of the carapace, or 

 one-fifth of that of the animal, with the first joint lamellar and nearly equalling the 

 third in length, both being longer than the second. 



" Second pair of antennae with the scaphocerite four times longer than the last joint 

 of the peduncle and extending nearly as far as the extremity of the peduncle of the first 

 pair. 



" Second, third, fourth, and fifth somites of the pleon armed each on the dorsal surface 

 with a sharp tooth ; sixth somite one-seventh of the length of the animal, longer than 

 the fourth and fifth somites combined, longer than the telson, and equal to the first 

 and second somites united ; not quite twice as long as it is broad. 



■' Pleopoda very slender. 



" Rhipidura with the external plate armed with a small tooth on the outer margin, 

 nearer the base than the apex." 



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



Habitat. — September 12, 1875, between Japan and Honolulu, South Pacific Ocean. 



Station 256, July 21, 1875 ; lat. 30° 22' N., long. 154° 56' W.; north of the Sandwich 

 Islands; depth, 2950 fathoms; bottom, red clay; bottom temperature, 35°'2. 



" Greenland " (Kroyer). 



Port Jackson, Australia, at night. 



The rostrum is waved and produced to a length equalling half that of the ophthal- 

 mopod ; the carapace, without the rostrum, is about one-third the length of the animal. 



Pleon with the first five somites subequal, the fifth being rather the shortest ; the 

 first is smooth ; the second, third, fourth, and fifth are armed with a long slender dorsal 

 tooth, situated in front of the posterior margin ; the sixth somite subequal to the two 

 preceding, and about as deep as half its length. 



Telson (fig. lz) about half the length of the sixth somite, broad at the base and 

 gradually tapering to the extremity. 



The ophthalmopoda are long, and have the stalk slender, and the ophthalmus broad 

 and reaching to the extremity of the first two joints of the peduncle of the first pair of 

 antennae. 



(ZOOL. CHALL. EXP. PAET ML — 1886.) Fff 51 



