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



The ventral surface of the pereion is armed with three pairs of styliform teeth situated 

 between the coxa of the two or three anterior pairs of pereiopoda. 



Observations. — This genus corresponds much with Gonatonotus, A. Milne-Edwards, 

 described from specimens taken in the West Indies by M. A. Agassiz during the 

 expedition of the " Blake," and which he says approximates to Oplophorus. 



Campylonotus differs, however, in general appearance from Gonatonotus in having no 

 carinated tubercle on the third somite of the pleon, and in not having a finely serrate 

 carina on the dorsal median line of the carapace, but three or four large teeth in place of 

 it. It also differs structurally in having no basecphysis ("petit palpiform appendice") 

 attached to the pereiopoda, while small basecphyses exist on all the pereiopoda of 

 Gonatonotus, and in having the propodos of the second pair articulated near the middle, 

 and not inserted into an excavation in the anterior margin of the carpos. 



It corresponds with Goes' genus Caridion, except in not having the carpos biarticulate. 

 In Caridion also, judging by the European type, the second pair of pereiopoda is longer 

 than, but not so stout as, the first, and the carpos is as short, and articulates with the 

 propodos as in Campylonotus. 



The branchiae correspond more nearly with those of several genera of the Polycarpidea, 

 such as Pandalus, Heterocarpus, and Merhippolyte, in which the mastigobranchias are 

 short and rudimentary, rather than with those in its nearer congeners, Palaemon and 

 Oplophorus, among the Monocarpidea. The arrangement of the branchiae is given in 

 the following table : — 



Pleurobranchiae, 

 Artkrobrancbiae, 

 Podobranckise, 

 Mastigobranckiae, 



hi k 1 m n o 



The mastigobranchial plate of the second pair of siagnopoda extends posteriorly as 

 far as the penultimate pleurobranchiae, and has the extremity tipped with long hairs that 

 reach to the posterior limit of the branchial chamber. 



Geographical Distribution. — The specimens of this genus were taken most abundantly 

 in the channels among the rocky islands off the western coast of Patagonia, some specimens 

 having been taken at every station at which the Challenger dredged in that locality. 



The sexes are nearly equally abundant, but the males are smaller than the females, 

 and the ova are moderately large and numerous. 



Campylonotus semistriatus, n. sp. (PI. CXXVIII. figs. 1, 2). 



Carapace one-fourth the length of the animal, anteriorly produced to a rostrum 

 subequal to it in length, dorsally carinated from the posterior margin, and armed with 



