Mr. E. L. Layard on new species of Tanalia. 137 



Paludomus spiralis, Reeve. 

 I include in this group, from its resemblance to my Pal, palustris. 

 The only specimens I ever saw are in Mr. Cuming's cabinet. 



Paludomus dilatatus. Reeve. 



Operculum concentric ; nucleus subcentral, dextral. 



Hab. Ceylon, Rambodde Pass, mountain torrent. This species was 

 given to me along with Pal. globulosus ; I therefore know nothing of 

 its habits. 



Genus Tanalia, Gray. 



Tanalia loricata. Reeve. 



This species grows to its largest size in the Calloo ganga, above 

 Ratnapoora, where it is found in the most rapid foaming currents ad- 

 hering to rocks. It resorts to deep sandy pools and reaches at some 

 seasons, but apparently will not exist in a river devoid of rocks and 

 rapids. Most of the streams of the southern provinces answering to 

 this description contain it ; but I never met with it to the northward, 

 where the rivers become more sluggish. 



The mollusk is almost black. 



Tanalia crinascens, Reeve. 



I doubt this being more than a geographical variety of the preceding 

 species ; and not being aware that it had been separated from it, did 

 not pay attention to the operculum, though it evidently belongs to 

 this group. I have only received the species from one locality, 

 Kadaganava Pass, between Colombo and Kandy ; but have interme- 

 diate varieties, on which half the spines are solid, as in loricata, 

 half capped and hollow, as in crinascens. 



T. ^rea, Reeve. T. Layardi, R. T. undata, R. 



I seek in vain for sufficient distinction in these species to separate 

 them from loricata. Take a strongly-marked specimen of each, and 

 the division appears an excellent one ; place a hundred of each, and 

 the gradations are imperceptible. 



As far as my recollection serves me, there is nothing different in 

 the animals ; but as I was not aware of the separation of cerea and 

 Layardi, I did not closely scrutinize them ; however, of undata 

 dozens passed in review with careful survey. 



They are found with loricata and the pseudo-variety crinascens 

 before mentioned ; and the opercula are undistinguishable, save that 

 those of cerea having a wider aperture to fill, are larger and not 

 quite so angular. I look upon them as varieties of loricata. 



Tanalia Gardneri, Reeve. 



Operculum not distinguishable, except in size, from that of lori- 

 cata. In very large specimens the angle is often very great, and is 

 bent outward on the exterior side. 



Hah. I found this species in a waterfall pool at Tambillichna, 

 below Ratnapoora ; also in the Calloo ganga, but only in the most 

 rapid current, mixed with loricata and the next species. 



