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



Oodeopus geminidentatus, n. sp. (PI. CXLII. fig. 1). 



Carapace smooth ; anteriorly produced to a long rostrum, serrate at the lateral margins. 

 Fronto-lateral angle produced to a long, style-like tooth. 



Pleon long and narrow ; five anterior somites subequal. First somite dorsally smooth, 

 second armed with two teeth at the posterior margin, one on each side of the median 

 line ; third, fourth, and fifth somites similarly armed with two teeth ; sixth somite about 

 the length of the two preceding, and posteriorly armed on the dorsal surface with one 

 long, spine-like tooth. 



Telson a little shorter than the sixth somite. 



Habitat. — Cape York, September 8, 1874. 



The carapace is about one-fourth the length of the animal, slightly elevated to a 

 small protuberance on the dorsal crest over the frontal region, and anteriorly produced 

 to a rostrum that is one-third longer than the carapace, dorsally depressed, and laterally 

 widened and tapering to the apex, the margin long, serrate with a number of small 

 teeth ; the median line on the lower surface of the rostrum is depressed below the lateral 

 margins. The orbital excavation is slight, and extends nearly to the fronto-lateral angle 

 of the carapace, which is produced to a long, narrow, and spine-like tooth, reaching as far 

 as the extremity of the peduncle of the second pair of antennae ; posteriorly to this tooth 

 the lateral margin of the carapace is finely serrate for a short distance, whence it is smooth 

 to the posterior extremity. 



The pleon is about three times as long as the carapace, the first somite is dorsally 

 smooth, but all the others are armed; the four succeeding somites have each two teeth 

 at the posterior margin, while the lower marginal angles are slightly produced to a small 

 obtuse point ; the sixth somite is dorsally armed at the posterior margin with a long, 

 slender tooth, and on each side at the infero-distal angle with a sharp tooth. 



The telson (fig. lz) is nearly as long as the sixth somite ; the lateral margins are 

 nearly parallel, and terminally slope to a point in the median line, where it is armed 

 with a long, robust spine, on each side of which there are eight spines, four smaller and 

 three succeeding larger ones, and a distant one still smaller on the outer margin. 



The ophthalmopoda are short, and terminate in a large, oval-shaped ophthalmus, the 

 larger diameter of which is near the posterior extremity. 



