602 



THE VOYAGE OF H.M.S. CHALLENGER. 



half the length of the leg and divided into seven articuli, the first two of which are short, 

 the third, fourth, and fifth being subequally long, the sixth short, and the seventh about the 

 same length as the fifth. The fingers of the chela are a little shorter than the palm of the 

 propodos, and the coxa is furnished with a rudimentary mastigobranchia, similar in form to 

 that on the preceding pair, and corresponding with those on the following pereiopoda. 

 The last three pairs of pereiopoda are simple, the dactylos being slightly curved and fur- 

 nished with a few spines and a small tooth on the inner margin near the unguis (m). 



The pleopoda are biramose. 



The telson is nearly as long as the lateral plates of the rhipidura, posteriorly tapering 

 and truncate, the distal margin being fringed with hairs, and bearing a spinule at each 

 angle, and the dorsal surface bearing two rows of spinules, four in each row, which 

 Leach thought sufficient to make a specific distinction 



Length, entire, .... 

 of carapace, 

 of rostrum, 

 of pleon, 



of third somite of pleon, 

 of sixth somite of pleon, 

 of telson, 



Habitat. — Station 49, May 20, 1873; lat. 43° 3' N., long. 63° 39' W.; south of 

 Halifax; depth, 85 fathoms; bottom, gravel, stones; bottom temperature, 35°. 

 Numerous specimens of both sexes and all the varieties. Associated with Spirontocaris 

 spinas. Dredged. 



A peculiar parasitic Cirriped was found on this species which will be described by Dr.' 

 Hoek in the Appendix A to this Report. 



Nauticaris, n. gen. 



Carapace one-third the length of the animal, anteriorly compressed, dorsally crested, and 

 produced to a well-developed rostrum, adorned with teeth on the upper and lower margins ; 

 orbital region without supraorbital teeth. Outer canthus defined by a small point ; an- 

 tennal tooth just behind the frontal margin, infero-lateral angle defined by a small point. 



Pleon smooth, third somite slightly arcuate. Sixth somite but little longer than the 

 fifth, and furnished with a movable spine at the posterior extremity of the lower margin, 

 just in advance of the articulation of the rhipidura. 



Telson tapering. 



Ophthalmopoda pyriform and furnished with a small ocellus. 



First pair of antennse carrying a strong stylocerite and terminating in two moderately 

 long flagella. 



