326 ashford: the action of the heart in the helicid^. 



Sometimes it was thin, pellucid and entire. At lower temperatures 

 it exhibited a crumpled, white fissured spot, always on the side of 

 the columella. Below or near freezing point it was always opaque 

 and papyraceous. An aperture was sometimes present, sometimes 

 absent, irrespective of temperature. Five times during the three 

 months the epiphragm was destroyed by extrusion, but was 

 invariably renewed the next day. That the animal fed on one, at 

 least, of these occasions was evident from the presence (Feb. 11) 

 within the epiphragm, of a mass of faecal matter absent the day 

 before. Zonites cellarius formed no epiphragm, in fact a consi- 

 derable part of the prosoma was outside the aperture during the 

 whole of the three months, and the upper tentacles, three parts 

 withdrawn, were frequently visible. 



If anyone feels disposed to follow up this enquiry in the case 

 of other species I would suggest H. caniiana as a suitable subject. 

 It is less hardy than most I have mentioned, and yet has a fairly 

 transparent shell. Great care must be taken to avoid the presence 

 of disturbing factors. Thus the shell should never be handled. 

 Contact with the warm fingers may have the effect of quickening 

 the pulse 10, 20 or even 30 per cent before a minute has elapsed, 

 means for avoiding this will suggest themselves. My own practice 

 has been to move the shell with a small stick on to a dead leaf and 

 so bring it under the lens if necessary. I also excluded from the 

 register all records of pulse taken when the animal showed signs 

 of motion. Exercise, in snails as in man, is always accompanied 

 with more rapid circulation, even if the motion be merely the 

 protrusion of the head from the shell in the one case, or in the 

 other the simple act of getting out of bed in the morning. 



J.C, iii., July, 1882 



