182 Prof. T. Kupert Jones on 



they terminate in a long acute point in the one case, and in a 

 " long obtuse point" in the other. The reason why, in my 

 former note, I was not in a position to deny positively that 

 these extremely rudimentary organs had lenses, was because, 

 although the ' Porcupine ' specimens showed not the slightest 

 trace of lenses, yet, as they had been preserved in glycerine 

 and subsequently transferred to spirit, it was possible that 

 this treatment might have destroyed lenses which had 

 existed. 



Mr. Bate inquired whether I could say there were eye- 

 stalks in the young of " Astacus ? zaleucus, Willemoes-Suhm, 

 Nephropsis Stewartii, Wood-Mason, and the blind prawns of 

 the North- American caves." Of the first two only the type 

 specimens are known. It is hardly likely, therefore, that I 

 should be acquainted with their young. With respect to the 

 " blind prawns of the North- American caves," I know of no 

 such Crustacea ; and suppose that " prawns " was a slip for 

 11 crayfish," and that he refers to the Cambarus pellucidus of the 

 Mammoth Cave of Kentucky. That crustacean has eyestalks 

 not only when it is young but in maturity also. " Like the 

 other animals living in caves, it is blind. The eyes are atro- 

 phied, smaller at the base, conical, instead of cylindical and 

 elongated as in the other species. The cornea exists, but is 

 small, circular, and not faceted ; the optic fibres and the 

 dark-coloured pigments surrounding them in all other species 

 are not developed " *. 



XXII. — Notes on the Palwozoic Bivalved Entomostraca. 

 No. XIII. Entomis serratostriata and others of the so- 

 called " Cypridinen " of the Devonian Schists of Germany. 

 By Prof. T. Rupert Jones, F.R.S., F.G.S. 



[Plate Xl.f] 



Introduction. — In the ' Annals and Magazine of Natural His- 

 tory ' for June 1873, pp. 413-416, is a list of the species of 

 Entomis with which I was acquainted at that date. These 

 included several Devonian species from Germany, and Silurian 

 species from Bohemia, known to me from figures only, as well 

 as some British Silurian% and Carboniferous species which 



* Hagen, I. c. p. 33. 



t This Plate has heen drawn under a grant from the Royal Society for 

 the illustration of fossil Bivalved Entomostraca. 



J Entomis aciailata, op. cit. p. 416, was from Peeblesshire, not the 

 "Pentland Hills." 



