Mr. W. H. Benson on the genus Ptcvocyclos. 345 



and nearly as long as the body j 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 short, 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,\>\\\. 

 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 j 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 Dr. 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 fur Naturgesch.' for 1837, on his species S. pic- 

 tum. 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. 11-14, pi. 2, on a shell which I had 

 discovered in the province of Bahar in the pi*evious 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 (hispidus and parvus) under the generic name of Sinra- 

 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) Troschel's character of Stega- 



