inhabiting India and China. 349 



It is a very local species, but abundant in the places indicated. 

 Besides size, it differs from the Chusan species in sculpture, in 

 its more angular form at the periphery, and in its less excavated 

 lower disc, and narrower umbilicus. It is somewhat singular 

 that the only species of Planorbis which have been observed with 

 internal laminae, should inhabit such widely separated localities 

 as westernmost Europe, the eastern part of Asia (both of them 

 insular situations), the north-western part of India, and the mouth 

 of the Ganges. Planorbis umbilicalis, nobis (Journ. As. Soc. 

 vol. v.), an allied Bengal form, is utterly destitute of any internal 

 teeth or laminae, as is also the species next to be described. 



3. Planorbis canosus, nobis, n. s. ' 



Testa nitida, luteo-cornea vel olivaceo-cornea, oblique et rude (prsecipue 

 subtus) radiato-striata, subdiaphana, supra depresso-convexa; spira 

 parvula, apice excavate ; sutura impressa; anfractibus 3|, ultimo 

 majori, extus depressiusculo, inferiie carinato, subtus planato, versus 

 umbilicum majorem leviter excavato ; apertura obliqua, sagittiformi, 

 margine superiori arcuato, prominente, inferior! recedente, recto. 



Diani. maj. vix 6 mill., minor 5, axis 1 J. 



Hab. in stagno prope urbem Moradabad, agris Rohillanis. 



Less abundant and still more confined in locality than PL Ca- 

 lathus. The specimens taken by Dr. Bacon and myself were 

 supposed to be merely a large variety of that species, but on 

 clearing them, lately, from a thick ochreous deposit with which 

 they were disfigured, I perceived that not only were they 

 destitute of internal laminae, but that the shells were more de- 

 pressed and more angular at the keel, and that the relative pro- 

 portions of various parts differed. 



4. Planorbis Cantoris nobis, n. s. 



Testa nitidula, cornea, subdiaphana, radiato-striata, depressa, supra 

 convexiuscula, spira planata, apice concavo, sutura bene impressa ; 

 anfractibus 5^, convexiusculis, lente crescentibus, ultimo antiee 

 majori, subtus convexo, periphaeria subcarinata ; umbihco aperto, 

 profundiusculo ; apertura obliqua subcordiformi, margine supra 

 valde arcuato, fuscato, infra leviter rotundato. 



Diam. maj. 7, minor 6\, alt. 2 mill. 



Diam. spirse 3^ ; lat. anfract. ult., antiee, 3 mill. 



Hab. in stagnis Bengalensibus prope castra Barrackpore. Teste Theo. 

 Cantor. 



This shell, of a sublenticular form, is intermediate between the 

 subtrochoid species and the more symmetrical smaller Planorbes. 

 It comes much nearer to PL convexiusculus, Hutton, Journ. As. 

 Soc. Calcutta, July 1849, than P. umbilicalis, nobis, which, from 

 the tenor of his foot-note in page 657, Capt. Hutton has never 

 seen. The forms of the European and American shells with 



