878 



THE VOYAGE OF H.M.S. CHALLENGER. 



the posterior extremity of the fourth somite, each two succeeding somite is shorter than 

 the preceding, and is serrate along the dorsal margin and posteriorly produced to a 

 small tooth ; the fifth somite is nearly as long as the two preceding, it is dorsally serrate 

 and posteriorly projects to a strong tooth, but not more than half as long as the tooth 

 on the second somite ; the sixth somite is subequal with the length of the fifth, 

 cylindrical, dorsally smooth, and posteriorly produced at the posterior extremity to a 

 small tooth ; the lower lateral angle is truncate. 



The telson (fig. 2z) is little more than half the length of the preceding somite, slightly 

 enlarging posteriorly, the posterior margin being armed in the median line with a long 

 and straight tooth, and at the lateral angles with a slightly curved spine, the inter- 

 mediate space on each side being fringed with small and finely ciliated hairs. 



The ophthalmus is long, ovate, and tapers to a narrow, anteriorly projecting point, 

 the peduncle being invisible. 



The first pair of antennae is about half the length of the rostrum, and supports two 

 rudimentary flagella. 



The second pair of antennae carries a broad and foliaceous scaphocerite that is scarcely 

 half the length of the rostrum and terminally fringed with long hairs, as also is the 

 inner margin ; the flagellum as yet is only rudimentary. 



The oral appendages have not been examined, and the gnathopoda and pereiopoda are 

 as yet in the biramose condition common to an early and immature state of the Macrura. 



The pleopoda are in an incipient condition, except the sixth pair, which is about 

 two-thirds the length of the telson, the two branches are subequal in length, the 

 outer being armed on the outer distal angle with a long sharp tooth ; the inner branch, 

 as well as the inner margin of the outer branch, is very thickly fringed with fine 

 ciliated hairs. 



Habitat. — New Hebrides, August 23, 1874 ; Sibago, Philippines, and Cape Howe, 

 Australia. 



A slight variety of this species (fig. 3) was taken off Cape York, in which the serrature 

 behind the fronto-lateral angle of the carapace is continuous only for a short distance, 

 and there is no serrature on the dorsal surface of the rostrum ; the pereiopoda are in a 

 more advanced but still biramose condition. 



