no PATELLA-PATINA. 



The shell has the contour and texture of Helcion but is generally 

 thinner and the radiating sculpture is obsolete. 



P. PELLUCiDA Linne. PI. 51, figs. 4, 5, 9, 10. 



Shell thin, oval, elevated, the apex curved forward, near the an- 

 terior end. Surface polished, smooth except for very faint radiating 

 stripe. Dark olive or brownish horn-color, reddish or blackish at 

 the apex, and usually having a few radiating interrupted lines of 

 vivid blue. Interior brownish, reddish or dusky within the cavity. 



Length 20, breadth 15, alt. 8 mill. 



Lofoten, Norivay, to Caseaes Bay, Portugal. 



P. pelhicida L., Syst. Nat. x, p. 783. — Forbes & Hanley, Hist. 

 Brit. Moll, ii, p. 429, t. 61, f. 34 ; t. AA, f. 1 (animal).— P. coerulea 

 Pult., Cat. Dorset., t. 23, f. 6.— P. bimaculata Mont., Test. Brit., p. 

 482, t. 13, f. 8.— P. coiruleata Da Costa, Brit. Conch., p. 7, 1. 1, f. 5, 

 6. — P. elongata and elUptica Flem., Encyc. Edin., t. 204, f. 2, 3. — 

 P. cornea Pot. & Mich., Galerie Douai^ p. 525, t. 37, f. 5, 6.—? P. 

 intorta Pennant. — P. minor Wallace and P. cornea Michaud, 

 teste Jeffr. — Patina pellucida Leach, Moll. Gt. Brit., p. 224. — Dall, 

 Amer. Journ. Conch, vi, p. 280, t. 16, f. 30 (dentition). — Helcion 

 pellucidum Jeffr., Brit. Conch, iii, p. 242, t. 5, f. 4. — Nacella 

 pellucida Sars, Moll. Reg. Arct. Norv., p. 119, t. 2, f. 8 (dentition). 

 — P. cypridium Perry, Conchology, t. 43, f. 6. — P. Icevis Pennant, 

 Brit. Zool. iv, p. 144, t. 90, f. 151. — Patina Icevis Leach, I. c, p. 224. 

 — Patella cornea Heebling, Beitriige zur Kenntniss neuer u. seltener 

 Conchyl., in Abhandlungen einer Privatgesellsehaft in Bohmen zur 

 Aufnahme der Matheraatik, der Vaterliindischen Geschichte und 

 der Naturgeschichte, iv, p. 107, t. 1, f. 8, 1779. 



A delicate cap-shaped shell, common on fronds of laminarise 

 throughout the seas of northern Europe. 



Var. LiEVis Pennant. PI. 51, figs. 6, 7, 8. 



Shell more erect, the summit more nearly central ; solid, thick^ 

 more obviously radiately striated and having coarse concentric 

 wrinkles. Length 22, breadth 18-20, alt.- 8-10 mill. 



The distribution is the same as the typical pellucida. The differ- 

 ences are the result of station, the kevis living imbedded in the 

 stems of fuci. Specimens of all sizes may be found having the typi- 

 cal kevis fi)rra, but frequently a hwis is surmounted by an earlier 

 growth of the pellucida type, like the similarly caused forms 

 of P. granularis, compressa, Acnum pelta, etc., etc. 



