NOTES ON PALUDESTRINA JENKINSI. 289
shown to be a widely distributed form, occurring at Port Stewart
(Co. Derry), St. Johnstone and Carrigans (Co. Donegal),
Culmore (Co. Derry), Kenmare (Co. Kerry), Newry (Co. Down)
and Antrim at the mouth of the Sixmilewater.
The opinion has been expressed that the species is identical
with the West Indian P. crystallina Pfr. Certain it is that the non-
carinated examples of these species are very near to each other,
but in the carinate specimens the carinae in P. jenkinsi are by no
means so pronounced as in P. crystallina. In the latter species they
may rather be described as a series of spines which thus contrast
with the tufts of the former. In addition, the Rev. Prof. H. M.
Gwatkin informs us that the radulae differ. He writes :—"In
the central tooth P. crystallina has a narrower form, a more
decided anterior concave sweep, and more conspicuous basal
teeth nearer to the posterior edge. But the central denticle is
less developed than in P. jenkinsi. So far the specific distinction
is clear. My doubt is that I have a strong impression that one
or the other is very variable." From these facts we venture to
think that P. jenkinsi is a good species. It has been figured three
times:—by A. J. Jenkins in Science Gossip (1890), vol. xxvi.,
pp. 104-105 ; by Walter Crouch in Essex Naturalist (1890),
vol. iv., p. 213 ; and by L. E. Adams in The Collector's Manual of
British Land and Freshwater Shells (2nd Edition). Its habits have
been well described by Mr. Jenkins as well as its distribution
(op. cit., and Essex Naturalist (1891), vol. v., p. 232). Two