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THE VOYAGE OF H.M.S CHALLENGEE. 



projects to a small tooth ; the fifth is like the fourth but not so deep, and the postero- 

 lateral angle projects to a point. The sixth somite is longer than the fifth, more 

 compressed, and not posteriorly armed with a tooth on the dorsal surface. 



Fiq. 72. — Bentlwocaris stylorostratis, from a drawing by Dr. B. von Willemoes Suhm. 



The telson is as long as the sixth somite and gradually tapers to a point. 



The ophthalmopod (fig. 4a) is short and bulbous. The ophthalmus is brown in 

 colour and of smaller diameter than the base, which is furnished on the inner and upper 

 surface with a translucent papilla, in which there appears to be no ocellus, but an 

 opaque mass at the distal extremity. 



The first pair of antenna? is large and massive ; the first joint of the peduncle is 

 excavate on the upper surface and furnished with a small stylocerite on the outer 

 margin ; the second and third joints are short and thick, and each is furnished on the 

 under surface with a fasciculus of long plumose hairs. The outer flagellum is large 

 and broad, the upper surface being smooth and the under surface longitudinally 

 excavate and thickly covered with soft membranous cilia ; the terminal portion of the 

 flagellum rapidly tapers to a long and slender extremity. The flagellum on the inner 

 side is long, slender and cylindrical. 



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

 peduncle ; the second joint is armed on the outer distal angle with a sharp tooth, and 

 on the inner with a scaphocerite that is about two-thirds the length of the first pair of 

 antennas, foliaceous on the inner margin, which is fringed with hairs, and rigid on the 

 outer, but not armed with a tooth at the distal extremity, unless it be broken off. 



The mandible (fig. 4cZ) is furnished with a two-jointed synaphipod, the basal joint being 

 long, and the distal short, ovate and fringed with hairs, some of which are plumose. 



