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



apophysis of the mandible ; the rest of the carapace is smooth both at the margin and on 

 the dorsal surface. 



Pleon having the anterior five somites subequal ; the first and second are dorsally 

 armed with a small tooth, anteriorly to the posterior margin, so also are the third, fourth 

 and fifth somites, but on these each tooth is twice as long, and nearer to the posterior 

 margin. Fifth somite with a small tooth above the infero-posterior angle. Sixth somite 

 as long as the four preceding combined, and armed at the posterior dorsal margin 

 with a slender tooth. 



The ophthalmopoda are long and clavigerous. 



The first pair of antennae has the peduncle rather longer than the ophthalmopoda, and 

 has the first joint long and the two following short, of which the third is shorter than the 

 second, and terminates in one long and robust flagellum (broken), and one short and 

 uniarticulate ; the base of the first joint is enlarged, armed with a tooth on the outer 

 margin, and contains an otolith. 



The second pair of antennae has the flagellum broken off at the extremity of the 

 peduncle, which carries a long, narrow scaphocerite, armed on the outer margin with a 

 long tooth (2c) that commences at some distance from the extremity and passes beyond it. 



The appendages are all in an immature condition, but the second and third pairs of 

 pereiopoda exhibit signs of an incipient chelate character. The fourth and fifth pairs are 

 present in a budding condition ; the fourth is larger than the fifth. 



The pleopoda are long, slender and single-branched, having the bud of the second 

 branch present on the last two pairs only. 



Terminal or lateral branch of the rhipidura long and narrow ; the outer longer than 

 the telson, and furnished with a tooth near the middle of the outer margin, beyond which 

 it is fringed with long hairs as is also the inner plate. 



Length, 4 mm. (0'17 in.). 



Habitat. — North of New Guinea. 



Observations. — This specimen was taken associated with the preceding, to which it 

 bears considerable resemblance, but differs from it in several details which I believe to be 

 dependent upon development. 



The dorsal teeth on the pleon and that on the lateral margin cf the fifth somite probably 

 disappear with growth ; the form of the scaphocerite becomes broader and the subapical 

 tooth smaller, the rostrum shorter, and the terminal appendages of the telson probably 

 disappear in the adult animal. But the two last pairs of pereiopoda, which are now in a 

 budding condition, probably become developed into rudimentary or imperfect appendages, 

 as seen in Sergestes ; and the lateral dorsal teeth on the hepatic region of the carapace 

 probably continue as a more or less important feature, and therefore suggest that this 

 specimen when mature is specifically distinct from the preceding. 



