132 JOURNAL OF CONCHOLOGY, VOL. 9, NO. 5, JANUARY, 1899. 



but not according to his figures. The figures in " British Mollusca" 

 are very good. 



R. membranacea var. minor Jeffr. — Jersey ; Guernsey ; Pen- 

 zance ; Torbay; Killala ; raised beach at Shewalton, Ayrshire (Scott)! 

 Var. venusta Phil. — Near Weymouth. The aperture in this 

 variety is smaller. It is figured in " British Mollusca," but not well. 



Typical specimens from Bantry are remarkably stumpy and solid, 

 while those from Jersey are characterised by slenderness and elegance. 

 Plenty of typical specimens are smooth, and plenty of the var. elata 

 are ribbed, while the range in size is very great. The var. minor is 

 1 1 to 2 lines in length, but some very dwarfed specimens of the type 

 from Guernsey are of the size and shape of R. costata. Some mon- 

 strosities of the var. elata from Portland have the base of each whorl 

 keeled. 



R. violacea Desm. — Jersey ; Bantry Bay ; Birterbuy Bay ; Killala 

 Bay ; Bundoran. 



Var. ecostata Jeffr. — Borough Island, S. Devon, one specimen 

 only of the male shell ; Bantry and Killala Bays. 



In a miscellaneous assortment of the shells of this species they 

 appear to be all sizes, in consequence of the large males being equal 

 in size to the small females ; but specimens from the same locality 

 have the sexes always sharply defined by a great difference in size, 

 the males being less than half the size of the females, and much 

 less numerous. 



R. COStulata Aid. — There has been much confusion on the part 

 of writers in the identity of this species and several allied forms. 

 Monterosato considers R. guerini Reel, to be R. costulata Aid., while 

 von Mohrenstern considers it a distinct species. Dr. Watson is of 

 opinion that "the whole group absolutely requires revision, and 

 nothing but worse confusion can result from mere partial meddling 

 with it." He further considers R. costulata and R. similis, as well as 

 " a great many other species, British and foreign, to be mere varieties 

 of R. fiarva." But I believe this to be going a little too far as regards 

 our British species, which I consider to be well defined as species 

 according to the fair interpretation of the term. I have some British 

 variations of R. costulata that are shaped as R. parva, R. membra- 

 nacea, and R. violacea, but they all retain the other characteristics of 

 R. costulata Aid. ; and although I have collected many examples from 

 many places in Britain, I have never met with a doubtful form or a 

 connecting link between any of these species. 



R. Striata A. Ad. — This lives under stones among shelly gravel 

 at low water, and is dredged dead at all depths. The longitudinal 

 ribs are of a variable character, but are always present. 



