REPORT ON THE CRUSTACEA MACRJJRA. 



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The specimen under examination had been evidently approaching a period of 

 moulting. Having been stained, the subjacent new tissue shows the new dorsal 

 tooth of the sixth somite ready to take the place of the previous one, but shorter and 

 less important, while that on the fifth is still less so, and that of the fourth appears to 

 be wanting. 



It closely resembles Sergestes longirostris (PI. LXXV. fig. 3), which was taken off 

 Samboangan, from which, however, it differs in the presence of the two very long dorso- 

 lateral teeth. 



Sergestes cormttus, Kroyer. 



Sergestes cornutus, Kroyer, Monograph. Fremstilling af Krseb. Sergestes, pp. 33, 61, Tab. ii. 

 fig. 2, a-t. 



" Rostrum very prominent and acute, equal to or exceeding half the length of the 

 ophthalmopod. 



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

 first pair of antennae, having the ophthalmus not distinct from the pedicle and 

 broader than long ; the breadth being rather more than one-third of the length of 

 the ophthalmopod, but the length not half that of the ophthalmopod. 



" First pair of antennae has the peduncle very slender and about one-seventh shorter 

 than the carapace ; third joint longer than the clavate first joint, and much longer than 

 the second. 



" Second pair of antennas having the last joint of the peduncle linear, and nearly half 

 the length of the scaphocerite. 



" Sixth somite of the pleon nearly one-sixth of the length of the animal, but shorter 

 than the fourth and fifth somites combined, or the first and second, very little longer 

 than the telson, but twice as long as broad. 



" Pleopoda having the branches long and slender, but the basal joint of the fifth pair 

 only twice longer than broad. 



" Rhipidura having the outer ramus armed with a tooth one-third distant from the 

 terminal apex. 



" Habitat. — Greenland " (Kroyer.) 



I have not been able to determine any form that wholly corresponds with this species, 

 but that which I have named Sergestes nasidentatus differs from it in the length of the 

 ophthalniopoda, which are about four times the length of the rostrum, or subequal to the 

 first joint of the peduncle of the first pair of antenna?. It was taken off the southern 

 coast of South America, near the island of Juan Fernandez. 



