Mr. W. H. Benson on the genus Pterocyclos. 845 



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 i-ather 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 -^. Alni,hvit 

 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 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 fiir 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. 1 1-14, pi. 2, on a shell which I had 

 discovered in the province of Bahiir in the previous year. Three 

 capital figures of my third variety of Pterocyclos i-upestris, drawn 

 and engraved by the lamented James Prinscp, 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 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 n'ith 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- 



