220 F. Stoliczka — Notes on Terrestrial Mollusea. [No. 3, 



All the species which I examined are ovo-viviparous, as already 

 noticed by Benson in P. achatina. One specimen of P. cyclaspis 

 had three well* developed embryos, each consisting of three con- 

 volutions, regularly coiled in and enclosed in a thin soft sac of cal- 

 careous granules, loosely jointed together. A specimen of P. pina- 

 cis had the whole uterus filled with 13 eggs, in different stages 

 of development. The first were perfectly developed, composed of 1\ 

 whorls, distinctly discernible. The youngest only consisted of a 

 yolk mass, darker internally than externally and folded on itself 

 hemispherically, like an enrolled Oniscus. 



The jaw is very thin, horny, semi-elliptical, with a small anterior 

 median projection ; it is marked transversely with a great number 

 of more or less distant grooves which divaricate in the centre. 

 The surface often besides shews in a transparent light a very fine 

 concentric striation, either on the entire jaw, or only on its median 

 portion. 



The radula is long and of moderate width, composed of numer- 

 ous (about 100, or slightly more) transverse, more or less angular 

 rows, each containing between 60 and 70 teeth. The centre tooth 

 is in achatina and cyclaspis very small, long, recurved and pointed 

 at the end. The lateral teeth, which gradually decrease in size to- 

 wards the outer margins, are of a subquadrangular shape ; each 

 possess a long rather obtuse, robust cusp, and besides that on the 

 outer side an inflected margin with 2 or 3 small cusps, and on 

 the inner a marginal cusp. The outermost teeth become quite 

 simple in shape, only one or two of the outer denticles being in- 

 dicated. On the last rows of the radula, the teeth have generally 

 only the robust cusps developed. 



On comparing the jaw of Plectopylis with that of Clausilia, it will 

 be seen that both are similar in structure, but the shape is different 

 and the transverse sulcations are only indicated in the latter genus. 

 Much greater is the similarity of the Plectopylis jaw with that 

 of Cylindrella, as published by Crosse and Fischer in Journ. de 

 Conch., vol. x, 1870, p. 5, &c, pi. iii and iv, with the exception 

 that the median projection is wanting in the Cylindrella jaw. 



The arrangement of the teeth of P. achatina and cyclaspis also 

 agrees with that of Cylindrella in the very small size of the centre 



