845 
Mr. W. II . Benson on the genus Pterocyclos. 
and nearly as long as the body ; the tips of the third and of the 
following joints and the whole of the latter joints are black ; the 
fourth joint is rather more than half the length of the third ; the 
fifth is very much longer than the fourth ; the sixth is a little 
shorter than the fifth ; the seventh is extremely shoi% and almost 
obsolete : the nectaries are extremely short : the legs are yellow ; 
the feet and the tips of the thighs and of the shanks are darker : 
the wings are colourless ; the veins are like those of A. Alni, but 
less straight and much more clouded ; the third vein sends forth 
its first fork a little beyond one-third and its second fork a little 
beyond two-thirds of its length ; the fourth vein is sometimes ob- 
solete, sometimes indistinctly visible. 
Length of the body 2 lines ; of the wings 5 lines. 
[To be continued.] 
XXXVII. — Note on the Cyclostomatous genus Pterocyclos, Ben- 
son (Steganotoma, Troschel). By W. H. Benson, Esq., late 
Bengal Civil Service. 
Among I)r. Philippics ^ Abbildungen und Beschreibungen neuer 
oder wenig gekannter Conchylien,^ vol. i. Cassel, 1842-45, ap- 
pear two species of operculated land-snails under the generic title 
of Steganotoma, Troschel, as founded by that author in ^ Wieg- 
mann^s Archiv fiir Naturgesch.^ for 1837, on his species S. pic- 
turn. This genus was anticipated by me under the name of 
Pterocyclos in the ' Journal of the Asiatic Society of Calcutta ^ 
for January 1832, vol. i. pp. 1 1-14, pi. 2, on a shell which I had 
discovered in the province of Bahar in the previous year. Three 
capital figures of my third variety of Pterocyclos rupestris, drawn 
and engraved by the lamented James Prinsep, Secretary of the 
Society, accompanied the paper. Six years subsequently Troschel 
published the type of the identical species, described in the In- 
dian Journal, as new. 
In November 1833 Dr. Pearson (J. A. S. vol. ii.) added two 
species (Jiispidus and parvus) under the generic name of Spira- 
culum, from the north-east frontier of Bengal, which were figured 
by Prinsep in tab. 20 of that volume. 
In the fifth vol. of the ^ Zool. Journal ^ for 1834, p. 462, the 
attention of conchologists was called to the genus Pterocyclos in 
a slight notice. In June 1836 I published, in vol. v. of the 
J. A. S., further observations on the genus (after discovering the 
animal inhabiting the shell), together with remarks on its sin- 
gular operculum, and on Dr. Pearson^s two species, adding also 
the comparative characters of the living animals of Pterocyclos 
and Cyclostoma. 
In 1837 (as before mentioned) TroschePs character of Stega- 
