60 Mr. J. Wood-Mason on a new Genus 



This mud was not very productive, yielding only a few Annelids, 

 but was crowded with dead shells of Pteropods and Dentcdium 

 and with fragments of a large Brachiopod. 



It was in the last cast of the dredge that I had the good 

 fortune to capture the interesting addition to the crustacean 

 fauna of these seas described in the following pages. It is 

 closely allied to Nephrops norvegicus of northern European 

 seas — indeed, so closely allied that, were it not for the absence of 

 the squamiform appendage of the antennas, I should be under 

 the necessity of placing it in the same genus as a second species. 

 The absence of this appendage, however, leaves me no choice 

 but to establish a new genus for its reception. 



The discovery in these warm seas of a very near, of the 

 nearest ally, in fact, of so characteristic a cold-water species, 

 remarkable though it is, will not appear so surprising when 1 

 mention that my crustacean lived and burrowed in the 

 mud of the sea-bed at a depth of nearly 300 fathoms, in a 

 temperature certainly not exceeding 50° Fahr. 



One of the chief points of interest attaching to this new form 

 lies in the loss of its organs of vision by disuse, as in Galocaris 

 Macandrece, Bell, in Cambarus pellucidus (a member of 

 the same family as that to which Nephropsis belongs), and in 

 the other crustaceans and animals inhabiting the caves of 

 Carniola and Kentucky. I not only agree with Mr. Darwin* 

 in attributing the loss of the eyes to disuse, but I also regard 

 the great length and delicacy of the antennas and the great 

 development of the auditory organs as modifications effected 

 by natural selection in compensation for blindness f. 



Nephropsis, gen. nov. 



Diagn. Antennal scale absent. 



Nephropsis Steward, sp. nov. 



Body covered with fine rounded tubercles and with a short 



* Origin of Species, 5th edit. pp. 171-173. 



t Since these remarks appeared in the abstract of my paper (Proc. As. 

 Soc. Beng. 1872, viii. p. 151), Dr. Hagen's Monograph of N.-American 

 Asfacidce has reached Calcutta ; and from it I give the following extract, 

 on account of its obvious applicability to the species here described, merely 

 remarking that the perusal of it led me to note also the stoutness of the 

 rostrum and the great development of the cephalostegal spines in Nephropsis 

 as compared with the slendernessof the one and the minuteness of the others 

 in Nephropts : — " But it seems to be a somewhat well-recognized law in 

 Nature (Rathke, Metamorph. Retrogr. p. 135), that if any part is atrophied, 

 or stopped in development, the nearest parts show an abnormal increase of 

 development. This is apparently the case in C. pellticidus : the eyes are 

 atrophied ; and the rostrum, the fore border of the cephalothorax, the an- 

 tennal lamina, the basal joint of the inner antennae, and the epistoma 

 are altered or largely developed." — Op, cit. p. 34. 



