40 J. Wood-Mason — On N^ephropsis Steivarti. [No. 1, 



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 I mention the fact that my crustacean lived 

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

 a temperature not certainly 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 Calocaris MacAndrewece, Bell, 

 in Camharus pellucidus — a member of the same family as that to which Ne- 

 pTiropsis 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 antennae, and the great development of the auditory 

 organs as modifications effected by natural selection in compensation for 

 blindness.t 



Nepheopsis, gen. nov. 

 Diag. Antennal scale absent. 



Nepropsis Stewarti, sp. nov. PI. IV. 

 Body covered with fine rounded tubercles and with a short but dense 

 pubescence. The carapace is sub-ovoid, armed on each side, just externally 

 to the base of the rostrum, and behind the anterior margin, with an acute 

 forwardly directed spine ; a similar spine springs from each side of the ante- 

 rior margin itself at about the level of the upper surface of the antennal 

 peduncle ; the basis of each of these two spines is confluent with a conspicu- 

 ous convexity to be seen just behind it ; immediately in front of each of 

 these convexities lies a smooth, slightl}^ excavated surface bounded in front 

 by a curvilinear row of tubercles. The cervical suture, dividing the carapace 

 into an anterior or cephalostegal, and into a posterior or omostegal portion, 

 is broad and deeply impressed mesially and laterally, until it reaches the level 



* Origin of Species, 5fcli Edit., pp. lVl-173. 



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

 Ben. viii, 1872, p. 151) Dr. Hagen's Monograph of N. American Astacid(S 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 slenderness of the 

 one and the minuteness of the others in Nephrops : " But it seems to be a somewhat 

 well recognized law in nature (Rathke, Metamorph. Retrograd., p. 135) that if any 

 part is atrophied, or stopped in development, the nearest parts slow an abnormal in- 

 crease of development. This is apparently the case in C. pellucidus ; the eyes are 

 atrophied, and the I'ostrum, the fore border of the cephalothorax, the antennal lamina, 

 the basal joint of the inner antennae, and the epistoma are altered or largely deve- 

 loped." Op. Cit. 34. 



