462 Mr. W. H. Benson's Cone ho logical Notices. 



Pterocyclos bilabiatus, Bens. 



In the first number of the Journal of the Asiatic Society of Calcutta 

 (January, 1832,) I described under the name of Pterocyclos a genus 

 allied to Cyclostoma, and remarkable on account of the outer lip of the 

 shell being separated at its upper part from the body of the penultimate 

 volution, outside of which it rises vertically, somewhat in the shape of 

 a wing. 



Since my arrival in England I have satisfied myself by the inspection 

 of Mr. G. B. Sowerby's specimens, that his Cyclostoma hilahiatum is the 

 same shell at a more advanced period of growth ; when, in addition to 

 the notch and over-hanging wing at the upper part of the aperture, the 

 peristome becomes thickened and sinuated. Mr. Sowerby's specimens 

 were from Salem in the Madras Presidency ; mine were met with at 

 Sicrigully, a pass between the hills and the River Ganges, in Bahar. 



I am indebted to Mr. Sowerby for a specimen of Cyclostoma Petiveria- 

 num, Gray, and for the observation that it exhibits an approach to 

 Pterocyclos in the crude formation of a wing at the upper part of the right 

 lip. 



Cyclostoma Involvulus, Gray, MS. 



I found this beautiful species alive on the rocks of Sicrigully, and 

 among loose brick rubbish and under felled timber, in the fort of Raj- 

 mahal in Bahar on the 16th December, 1830. I also procured dead 

 shells from the rocks of Patharghata. It appears to be very plentiful in 

 all these situations. I never met with it to the westward, either in the 

 plains or among the rocks or hills of the Vindhyan ranges which border 

 those plains to the southward. I have seen a worn specimen in a collec- 

 tion of shells made 22 or 23 years ago in Ceylon. 



The young shell being destitute of the thickened and continuous 

 peristome, as well as of the rich orange colour which adorns that part> 

 might, if met with destitute of an inhabitant, be easily mistaken for a 

 Helix. The peristome when first reflected is also free from the orange 

 colour, which it does not acquire until thickened and fully grown. 



In its exterior anatomy the animal differs from that of Cyc. elegans. 



