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



First pair of pereiopoda having the propodos on the right side excessively developed, 

 being as long as the animal and nearly as broad ; the pollex is shorter than the dactylos 

 and bicuspidate ; the dactylos has the extremity hooked and the inner margin bears 

 one cusp. 



Pleopoda biramose, and furnished with a long and slender stylamblys. 



The posterior somite and telson are broken off. 



Length, entire, 



of carapace, 

 of rostrum, 

 of pleon, . 

 of large chela, 



18 mm. (0-7 in.). 



7 „ 



3 „ 



11 „ 



16 „ 



Habitat. — The label on the bottle containing the specimen says " Crustacean found in 

 Pearl oyster, Torres Straits, presented at Sydney, June 1874." It was, therefore, not 

 dredged by the Challenger, which did not arrive at Torres Strait until the following 

 September. 



Ibo, on the south-east coast of Africa ; between the folds of the mantle of Meleagrina 

 margaritifera, Lam. (Peters). 



The specimen, unfortunately, is damaged, but enough is preserved to show its true 

 character. The body of the animal is dorsally slightly arcuate from the frontal region to 

 the fifth somite of the pleon, which is bent downwards, and, judging from the character 

 of the curve, the sixth somite and rhipidura, in the living animal, are compressed 

 beneath it. The carapace is dorsally depressed and broadest over the genital and cardiac 

 regions ; anteriorly it is produced to a rostrum that continues the slight dorsal curve 

 and bends downwards at the anterior extremity ; it is about one-fourth the length 

 of the carapace, sharp at the point, and produced on the under side to a narrow or 

 compressed median ridge. From the sides of the rostrum the margin diverges to form 

 the orbits, which are deeply excavate, almost to the extent of the ophthalmopoda, 

 and defined at the outer angle by a sharp point between the orbit and the notch 

 excavated to receive the second pair of antennae, whence the carapace is deflected 

 abruptly beneath the peduncle and forwards beyond the base of the scaphocerite, 

 traversing in this incurved position the entire length of the carapace, the posterior 

 portion of which is membranous and flexible. 



The pleon has the first somite as broad as the carapace, over the postero-lateral 

 border of which it projects ; each somite gradually decreases in breadth and depth 

 posteriorly. The sixth somite and the rhipidura are wanting, but from appearances it 

 would seem that the posterior somite and the telson curve beneath the pleon, as repre- 

 sented by the dotted line on PI. CXXIV. fig. 1. 



The ophthalmopoda reach but little beyond the orbit, and are cylindrical and nearly 

 as broad as long ; the ophthalmus is wanting in colour. 



