MOLLUSCA OF INDIA. 199 
incision of the inner, and cowl-shaped process or wing of the outer, 
peristome. I have examined two or three species* of that genus 
with precisely the same result. Amongst the Pupinide, I have 
examined the animals of a variety of Pupina artata, Bens., and of 
Hybocystis gravida, B., but I could detect no trace of any process 
similar to that in Raphaulus. 
“The question of the use of these peculiar tubes in several genera 
of Indian Cyclostomacea, and the reason of their existence in only a few 
forms belonging to two different families (Cyclophoride and Pupinide) 
and by no means closely allied, has always appeared to me of con- 
siderable interest. The first and most natural suggestion which 
would occur to any one is that the tubes in question serve to supply 
the animal with air when the mouth of the shell is closed by the 
operculum. But, natural as this explanation seems, and despite its 
apparent confirmation by the discovery of the perforated process in 
the animal of Raphaulus, as described above, a very short considera- 
tion will show the difficulty of accepting it. For if additional 
means of breathing during estivation are essential to Raphaulus and 
Spiraculum, how do forms so closely allied to them as Pupina and 
Pterocyclos contrive to exist without them? And this is the more 
inexplicable because there are modifications of the shelly portions of 
those genera which apparently represent the sutural tubes of 
Raphaulus and Spiraculum, the close relation of perforations in the 
body-whorl and slits in the peristome being shown by such genera 
as Scissurella, Haliotis, and Stomatia, Fissurella and Emarginula, &e. 
Above all, what explanation can be adopted for the tube in Alycceus, 
perforated throughout its length, but closed at its posterior termi- 
nation ? 
‘“‘ It is extremely probable that there is a connexion between the 
existence of the sutural tubes in the land-shells mentioned and the 
well-known siphon of Ampullaria, which genus, from its habit of 
estivating in the dried mud of tanks, and its power of living for 
months without water, may almost be considered as an amphibious 
mollusk, and which approaches the Cyclostomacea most closely in 
the form of the animal. Another siphon-bearing species is Cam- 
ptonya, Bens., allied to Otina, which is by most conchologists classed 
with the amphibious Auriculacee, and I have recently obtained in 
Western India another generic type similarly furnished. It is 
closely affined to Camptonyx, being intermediate between that genus 
and Succinea. The two last-named shells estivate attached to rocks. 
I am inclined to think it possible that links yet remain to be dis- 
covered between all the siphon- and tube-bearing genera, in which 
the peculiar organization, common under various modifications to all 
of them, is more clearly adapted to the animal’s mode of existence 
than in the cases mentioned. It is extremely probable that such 
links may have existed and have become extinct. We can on this 
hypothesis easily conceive that their living representatives or, on the 
*“« Amongst others Péerocyclos pullatus, Beus., from Pegu, P. nanus, B., 
from the Nilgiris, and a species (a variety, perhaps, of P. alberst, Pfr.) from 
Arrakan.” 
