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



peduncle. At the base of the stylocerite on the outer margin is a smaller process, 

 that is slightly curved upwards and forwards and appears to assist in protecting the 

 ophthalniopod when at rest. The second and third joints are short and cylindrical, and 

 support two slender flagella, of which the outer is the more robust and the inner the longer, 

 equalling half the length of the animal. 



The second pair of antennae has attached to the first or coxal joint a well-developed 

 phymacerite. The second joint supports a scaphocerite that is about half the length of 

 the rostrum ; the inner and outer margins are subparallel, and the distal extremity of the 

 inner plate does- not project anteriorly beyond the extremity of the outer distal tooth ; 

 the terminal two joints of the peduncle are subequal in length and distally support a 

 flagellum that is longer than the animal. 



The oral appendages have not been examined, but they are probably only of generic 

 value. The second pair of gnathopoda is tolerably robust and has the terminal and 

 penultimate joints subequal, whereas the antepenultimate is somewhat longer. 



The first pair of pereiopoda is about the same length as the preceding pair of 

 gnathopoda but more slender, and has the terminal joint shorter than the penultimate. The 

 second pair has the right appendage wanting, but the left has the carpos long and about 

 equal in length to the rest of the pereiopod. The posterior three pairs are more slender 

 than in most species, and the teeth on the meros are smaller and less important. 



The first pair of pleopoda is unequally branched. In the solitary specimen, which is 

 a male, the inner and smaller branch is furnished near the distal extremity with a small 

 rudimentary stylamblys ; the second pair has the branches subequal and the inner and 

 posterior carries a long stylamblys, as it also does in the third pair, while the fourth has 

 one of smaller proportion and the fifth has none at all. The inner branches are more 

 slender and feeble than the outer. 



Heterocarpus ensifer, A. Milne-Edwards (PL CXII. fig. 4). 



Heterocarpm ensifer, A. Milne-Edwards, Arm. d. Sci. Nat., sit. 6, torn, xi., art. 4, p\ 8. 1881 ; 



Recueil d. Fig. Crust, 1883. 

 Pandalus carinatus, Sidney Smith, Bull. Mus. Comp. Zool., vol. x. p. 63, pi. x. figs. 2-2/., 



pi. xi. figs. 1-3, 1882. 



Carapace having seven carinas ; the central or dorsal is elevated into a crest, 

 continuous with the rostrum, which equals the length of the carapace. It is armed on 

 the upper surface with seventeen teeth, the posterior of which corresponds with the 

 pyloric region and they continue nearly to the apex of the rostrum ; the lower margin 

 is armed with twelve teeth, of which the posterior are the larger. 



The upper lateral carina extends from the gastric region to the posterior margin of 

 the carapace ; the median lateral carina passes from the tooth at the external canthus 

 of the orbit, with which it is confluent, to the posterior margin of the carapace ; the 



