94 Mr. W. H. Benson on new Terrestrial Shells from Ceylon. 



direct elongation of the internal coat, like the spores of the 

 Zygnemacese formed through conjugation, while the spores of 

 Bulbochatej and perhaps the spores of the Besmidicfc, likewise 

 originating through conjugation, behave in the same way as those 

 of SphcBToplea. This induces us to regard the latter fact as a 

 peculiar form of the ' alternation of generations/ if we deno- 

 minate the ' swarming-cells ' produced from the spores of Bulbo- 

 chcete and Spliceroplea an asexual generation, which by meta- 

 morphosis is converted at once into the Closterium-Wkc germ, 

 then by asexual division produces the sexual cells, till the cycle 

 is concluded by the formation of the impregnated spores. 



X. — New Terrestrial Shells from Ceylon, with a General List of 

 the Species inhabiting that Island. By W. H. Benson, Esq. / 



Cyclophorus Parma, nobis, n. s. 



Testa latissime umbilicata, planato-depressa, discoidea, tenuiuscula, 

 confertim et arcuatim sericato-striata, saturate castanea, flamnmlis 

 nonnullis pallidis spiram versus ornata, subtus interdum pallidiori ; 

 spira planata, apice nullo modo prominente, sutura profunda ; 

 anfractibus 5 eonvexis, ultimo antice descendente ; apcrtura valde 

 obliqua, ampla, ovato-rotundata, superne angulata, intus livide 

 caerulea ; peristomate duplici, interiori eontinuo, albido, ad dextram 

 expansiusculo, exteriori breviter interrupto, expansiusculo, fusco- 

 corneo ; margine columellari subtus recedente, dextro prorsum ar- 

 cuate ; umbilico latissimo, minime profundo. Operculo tenui, cor- 

 neo, .5y-spirato, suturis intus extusque pulchre carinatis. 



Diam. major 26, minor 23, alt. 6 mill. 



Hah. in regione montana Insulse Ceylon. Mus. E. L. Layard. 



There are two specimens in the cabinet of Mr. Edgar Layard. 

 The shell is easily distinguished from the other planorbular 

 Cyclophori of Ceylon by its dark colour and depressed form, 

 which recall those of Pterocyclos hispidus, Pearson, by its very 

 wide and shallow umbilicus, and by the size and peculiar position 

 of the aperture. The whorls of the operculum, which is of a 

 clear horn-colour, are less closely wound than in C, Cra^-a. 



Cyclophorus Crater a, nobis, n. s. ^ Af<^J^ y 



Testa late umbilicata, planulato-depressa, subdiscoidea, tenuiuscula, 

 radiatim et confertim ruguloso-striata, vix nitidula, fulvo-cornea, 

 raro castaneo-strigata; spira planulata, apice vix prominente, su- 

 tura profundiuscula ; anfractibus 5 convexiusculis, ultimo longe 

 lenteque descendente; apertura obliqua mediocri, subrotundata, 

 superne angulata, intus albida ; peristomate duplici, interiori con- 

 tinue, acute, breviter perrecte, exteriori expansiusculo, breviter 

 adnato, albido ; umbilico aperto, profundiuscule. Operculo tenui, 



