ZIRF^EA. 39 



across tlic disk, and it has a dorsal valve of wliicli P. crispala is 

 destitute. 



The animal is of a dark, smoky color ; the sii)hon is tapering, not 

 very long, and circularly wrinkled ; respiratory orifice striped alter- 

 nately black and white, the latter stripes marking the presence of 

 fourteen tentacular organs. 



Ociiiis ZIRF.EA, Leach (aR-vv). 1840. 

 Shell oval, hinge margin scarcely reflexed, joined by a horny 

 epidermis without accessory pieces, widely gaping in front. 



Zirfsea crispata. 



Valves touching at the middle of the base, and widely gaping at both ends; 

 a furrow passes from the beaks across the middle, in front of which are radi- 

 ating, toothed ribs. 



P/w/«.s crisjxUa, Linn. Syst. Nat. p. 1111 (1758). — Gmelin, Syst. p. .3216. — Sowerby, 

 Thcs. Conch— Cuv. Regno An. (Griffiths) pi. 113, fig. 3 (animal). — Brown, 

 111. Conch. 114, pi. 48, figs. 1-5. — Hanlev, Kec. Sh. 7, pi. 2, fig. 5; Ipsa Lin. 

 Conch. 26. — McGiLLiv. Moll. Abcrd. 306. — Thorpe, Br. M. Conch. 29.- Dk 

 Kay, Nat. Hist. New York, 247, pi. 32, fig. 506. — Lovi:N, Ind. Moll. Scand. 

 50. -1 Forbes and IIanl. Br. Moll. i. 114, pi. 4, figs. 3-5. — Donovan, Brit. 

 Shells, ii. pi. 62, 69. — Turton, Brit. Biv. 6; Conch. Diet. 146; Linn. Trans, 

 viii. 32. — Hutch. Dorset CataL 27, t. 3, fig. 4. — Wood, Gen. Conch. 81, pi. 15, 

 fi-i's. 3-5 ; Index, pi. 2, fig. 5. — Dillwyn, De.scr. Catal. 40. — Deshayes, Encyc. 

 Me'th. Vers, iii. 754, pi. 169, figs. 5-7. — Lamarck, An. sans Vert, vi 46. — 

 SciiROT. Einl. in Coneh. iii 541, No. 6. — Petiver, Ga/.oph. t. 79, fig. 13. — Flem. 

 Br. An. 456. 



Pholas hifrons. Da Costa, Brit. Conch. 243, t. 16, fig. 4. 



Pko'as latus, Lister, Conch, t. 436, fig. 279, and Append, t. 10, fig. 3. 



Solen crispus, Lin., Gmel. Syst. 3228. — List. Angl. t. 5, fig. 38. 



Pholas crispatus, Pennant, Brit. Zool. iv. 157, t. 43, fig. 2. — Montagu, Test. Brit. 23. — 

 Chemn. viii. 369, t. 102, figs. 872-874. 



Zirplum crispata, Chenu, Man. de Conch, ii. 6, figs. 26, 27. — Adams, Gen. ii. 327, pi. 

 89, fig. 5. 



Zirfica crispata, Gray, Cat. Br. Mus. (Biv.) 53. 



Shell oblong-oval, thick and strong, rounded posteriorly, nar- 

 rowed anteriorly into a sort of beak ; widely gaining at both ends, 

 the valves touching each other at only two points, viz. the hinge 

 and the middle of the base. Exterior surface marked with numer- 

 ous coarse, concentric ridges, which become lamellar on the ante- 

 rior half; the lamina3 are strongly toothed on their free edge, and 

 the teeth are disposed in radiating series. The valves are divided 

 into two nearly equal portions by a broad channel running from 



