OFF THE SOUTH-WEST COAST OK IRELAND. 323 



Molliisca West Coat<t of North America, in Brit. Assoc. Rep., 1863, 

 p. 537) ; but at a subsequent page (652), when be characterises the 

 genus, he substitutes the name Leptonyx, adding- " genns = Homalo- 

 poma, p. 537, noni. preoc.'^ I cannot find that this name has been 

 used, but as no description was given under the name Homalopoma 

 it may perhaps be best to retain the name which has been ado^Dted 

 by Dalh 



Leptothyea Bouenei, n. sp. 



Shell shortly conical, whorls six, girt (except at the base) with 

 numerous thread-like riblets, one of which is a little more prominent 

 than the rest, and forms a keel ; on the body-whorl there are six 

 riblets below and three above the more prominent riblet ; on the 

 penultimate whorl there are four below and four above ; no trans- 

 verse — that is, vertical sculpture ; apex rather blunt. Base convex, 

 without any trace of umbilicus or umbilical chink. Shell very solid. 

 Pillar lip slightly longitudinally channelled, the channel interrupted 

 in the middle by a transverse depressed nodule. Colour white ; in- 

 terior of shell and umbilical region highly polished and nacreous 

 with fine prismatic colouring. Operculum calcareous ; external sur- 

 face minutely granulated, rather sunken centrally, exhibiting no 

 trace of spiral arrangement ; internal surface chitinous, with central 

 nucleus and multispiral (11 — 12) whorls, the outermost whorl rapidly 

 enlarging. Lingual membranes have the lateral uncini extremely 

 numerous, hamate ; central teeth hamate, ten in number."^ Length 

 18 mm., breadth 20 mm. 



A single living specimen was dredged in 200 fath., 50° 50' 15" N., 

 11° 12' 30" W. 



This is a fine shell, and the largest species known of the genus ; 

 its operculum closely agrees in character with that of the type [L. 

 sanguinea, Linn.). 



From L. indiita, Watson (Report '^ Challenger " Gasteropoda, 

 p. 128, pi. vi, fig. 1), it differs in the more shortly conical form, and in 

 the total absence of the longitudinal '' infra- sutural puckerings '^ and 

 beaded riblets of the upper whorls ; while, on the other hand, the 

 spiral sculpture of the present form is much more developed. It 

 comes much nearer to the shell described by Dall [I. c, p. 352, pi. 

 xxxviii, fig. 6) as LeptotJiyra induta, var. alhida, but in that case the 

 riblets are fewer in number but much more pronounced ; and it may, 

 I think, be questioned whether Call's variety is really referable to 

 Watson's species. 



* The mounting is not very good, but I am unable to discover tlie usual central tootb. 

 In that position there seems to be a gap, on either side of which arc five teeth. 



