348 Mr. W. H. Benson on new species of Planorbis 
XXXI.—Characters of nine new or imperfectly described species 
of Planorbis inhabiting India and China. By W. H. Ben- 
son, Esq. 
1. Planorbis hemispherula, Cantor MSS.; Benson, Ann. Nat. 
Hist. vol. ix. 
Testa nitida, olivaceo-cornea, leviter exilissime radiato-str iata, subdia- 
phana, supra valde convexa, ae planulata, apice vix depresso ; 
sutura impressa ; anfractibus.4, ultimo extus declinato, majusculo, 
inferne obtuse subangulato, aia laminis raris radiantibus munito, 
subtus excavato; umbilico mediocri profundo, margine subangulato ; 
apertura obliqua subcordata, margine superiori arcuato, prominente, 
inferiori recedente. 
Diam. major 6 mill., minor 5, axis vix 3 mill. 
Tab. in insula Chusan Imperii Sinensis. Theo. Cantor. 
In describing this shell I formerly omitted any notice of the 
internal lamine, which indicate an approach to the more regular 
structure observable in the English Pl. lineatus (segmentina of 
Leach), as they were not very apparent through the substance of 
the shell in the specimen examined, and are not visible in the 
aperture. This species as weil as Pl. papyraceus of the same paper 
having been originally named by Dr. Cantor, will retain his name 
as the authority, although the asterisks denoting that circumstance 
have been too indiscriminately placed, as in the case of Helix ra- 
vida, mihi, and Novaculina (Solen) constricta, Lamarck. 
2. Planorbis Calathus, nobis, n. s. 
Testa nitidiuscula, albido-cornea, vel lutescente cornea, subdiaphana, 
exiliter radiato-striata, supra convexa, versus apicem planulata, 
apice concavo, sutura impressa; anfractibus 4, ultimo extus de- 
presso, inferne angulato, intus laminis denticulisque radiatis fre- 
quentioribus munito, subtus subplanulato, versus umbilicum an- 
gustum, profundum excavato ; apertura obliqua, cordato-sagittata, 
intus remote labiata, margine superiori arcuato, prominente, infe- 
riori subrecto, recedente. 
Diam. major 42, minor 4, axis 2 mill. 
Hab. in lacubus Bhimtal et Neini Tal, regionis Kemaonensis Hima- 
layanze ; necnon in stagnis nonnullis agri Rohillani, prope urbem 
Moradabad, Indize septentrionalis. 
In a note to a paper on the singular genus Camptoceras, and 
on the minute Melaniadous genus Tricu/a, contained in the 
‘Calcutta Journal of Natural History’ for 1842, I noticed the 
unusual structure of this species, but omitted to add a specific 
description. The shell belongs to the same type as the Chinese 
forms above described, and with the English species Pl. lineatus, 
and the Bengal P/. trochoides, forms a fourth species of analogous 
but varying internal structure. 
ayes 
