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. cvystallina 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. cvystallina. 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. 







i--- 



I. II. 



Fig. I. Palndestyina jenkinsi, Smith, typical form x 10. 

 ,, II. ,, ,, ,, smooth form x 10. 



Gwatkin informs us that the radulse differ. Pie writes : — " In 

 the central tooth P. cvystaUiua 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 (i8go), 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.y and Essex Naturalist (1891), vol. v., p. 232). Two 



