THE HELICOID GROUP CALLINA Lowe. 

 Description of a New Species. 



By Prof. T. D. A. COCKERELL. 



(■Read before tht Society, April 8th, 1922). 



The generic or sub-generic name Callina was founded by Lowe for 

 Helix rotula Lowe, a peculiar species confined to the small island of 

 Porto Santo. For the group of H. obserata Lowe and fausta Lowe, 

 confined to Madeira, he established the sub-genus Rimula, but this 

 name is pre-occupied. Pilsbry, in his guide to the study of Helices, 

 united Rimula with Callina as a single section of the sub-genus 

 Actinella Lowe. For the genus, including this and other sub-genera, 

 he used Geomitra, erroneously supposing that the earlier Ochthephila 

 Beck was preoccupied. 



It must be confessed that O. rotula stands conspicuously apart 

 from the others. It is a comparatively large shell, and when im- 

 mature is sharply keeled, with a very narrow aperture, the outer wall 

 fortified within by a strong white callus, and the opposite parietal wall 

 also presenting a distinct callus. This immature state might be taken 

 for the adult of a distinct species, on casual inspection. I described 

 the soft parts of a rotula from the top of the Pico do Castello as 

 follows : — Animal pellucid, with a pale reddish tint, greyer dorsally, 

 with the usual dark bands from tentacles ; mantle pale, with margin 

 of respiratory orifice opaque white ; oculiferous tentacles dark grey ; 

 two grey spots on front of head, and a grey dot above each. 



The species of Rimula I did not observe alive. Whether they 

 deserve a distinctive name is at present uncertain. The four species 

 and two varieties of Rimula hitherto described are from Madeira, but 

 I have been surprised to find one in the Pleistocene deposits of the 

 main island of Porto Santo. This shell, which I had mixed with a 

 quantity of Ochthephila compada portosanctana (Lowe), may be 

 described as follows : 



Ochthephila (Callina) crassiuscula sp. nov. 

 Shell with max. diam. 6, min. 5-2, alt. 4-1 mm.; very thick, low 

 conoid, with obtuse convex spire; whorls rounded, without any 

 keel ; whorls about six, slowly increasing, smooth, without granules 



