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



The plumes attached to the third pair of pereiopoda are affixed somewhat within the 

 basal extremity, and have the branchial processes somewhat longer at the base, beyond 

 which they rapidly and gradually decrease to the distal extremity, where they lose 



their lateral compression and appear as cylindrical papillae. The 

 plumes attached to the second pair of gnathopoda have the pro- 

 cesses very long and foliaceous at the base ; and after three or 

 four such processes rapidly decrease in size, and become cylin- 

 drical, the extremity of the stem of the plume terminating 

 obtusely. 



fig. i.— Branchial plume of p^g second pair of pleopoda is biramose, one branch extending 



from the terminal extremity of the basisal joint, the other, a long 



and slender one, from the side. The third and following are formed as in Callianassa, 



but support a small stylamblys tipped with minute cincinnuli, and both plates are fringed 



with hairs that are ciliated and multiartieulate. 



There is no doubt that this and the following specimens might have been considered 

 as one species had they been found in the same locality ; as it is they may probably 

 be a form common to species before they have attained their mature condition. 



This species was taken in comparatively shallow water at the entrance of Torres 

 Strait, off the south coast of New Guinea. 



Cheramus occidentalis, n. sp. (PL II. fig. 1). 



Carapace smooth, with a sharp rostrum, reaching nearly to the extremity of the 

 ophthalmopoda. Branchial region defined from the gastric. Telson long, quadrate ; 

 posterior margin rather narrower than the anterior, fringed with long ciliated hairs, and 

 having in the median line a strong sharp tooth, and two short sharp spines on the 

 posterior half of the lateral margins. 



Habitat.— Station 23, March 15, 1873; lat. 18° 24' N., long. 63° 28' W. ; off 

 Sombrero Island. West Indies ; depth, 450 fathoms ; bottom, Pteropod ooze. 



Length, 18 mm. (three-fourths of an inch). 



The carapace is laterally deep and generally smooth. The rostrum, laterally 

 compressed, projects anteriorly to a sharp point until it reaches nearly as far as the 

 extremity of the ophthalmopoda, which are pointed and rather longer than broad, 

 laterally compressed, and have the eye at the centre of the outer surface. The flagella of the 

 anterior antennas are nearly of the same size and length. The second joint of the second 

 pair of antennas is extremely long, and the last is short ; the rest of the appendage 

 is wanting. The pereiopoda are all broken off at the basisal joint, the two anterior 

 pairs of pleopoda are slender, the three succeeding are small and fringed with cilia. The 



