57 



exoticus, Cheran t. 20/. p. 2037, 2038. P. dispar? Lam. 

 Ostreea hybrida, Gmel. Dist. 1. 173. f. 10. 



T, rotundata, compressa, Isev'i, vel radiatim minutissime 

 striata ; auriculis planis, eequalibus ; colore cinereo vel 

 pallide fulvo, maculis magnis fuscis. Long. 1, 30; lat. 0. 37; 

 alt. 1, 30 ; poll. 



This is the true P. Pseudamusium of Klein, the P. Pseu- 

 damusium of Chemnitz being only a variety of his P. Danicus. 

 It varies from nearly smooth to being finely striated ; though 

 much smaller, it resembles P. Pleuronectes, &c. in general 

 form and appearance. Gambia, Africa. 



35. P. Greenlandicus. (pi. xiii. f. 40.) nob. 



T. aequivalvi, orbiculari, sub-compressa, sub-requilaterali, 

 pellucida, tenuissima, leevi; auriculis parvis, obtusangulatis, 

 anticis minoribus ; valva dextra lamina tenuissima, opaca, 

 induta. Long. 1 ; lat 0, 25 ; alt. 1 ; poll. 



This white transparent shell is brought from Greenland. We 

 are indebted to Albany Hancock, Esq., of Newcastle, for the 

 loan of the specimen figured. 



36. P. LATi-AURATus. (pi. xii. f. 20. 21.) Conrad. P. 

 Mesotimeris, Conrad, inclusus ? 



T. oblique sub-quadrata, inaequilaterali, tenui, sub-com- 

 planata; postice attenuata, auriculis obliquis, costatis; um- 

 bonibus antice reclinentibus ; costis duodecim rotundatis, 

 leeAdbus ; interstitiis concentrice striatis ; colore fusco, albo 

 fasciatim variegato. Yariat aurantiaco. Long. 1 ; lat. 0, 30 ; 

 alt. 1, 10; poll. 



Of a somewhat square shape, A^ery oblique, inequilateral, 

 thin, rather flat, posteriorly attenuated ; auricles wide, oblique, 

 costated ; umbones leaning considerably towards the anterior 

 side of the shell ; the ribs, twelve in number, are rounded and 

 smooth; the interstices concentrically striated; the colour 

 brown, variegated with zigzag marks of white ; there is also a 

 plain orange variety. CaUfornia. 



37. P. TUMiDus. (pi. xiii. f. 27. 28. 29.) Turton. 



T. rotundata, sub-compressa, parva, tentii, leevi; auriculis 

 magnis, sub-cequalibus ; colore pallide fulvo, rubro fulvoque 

 radiatim maculato, vel albo, vel luteo. Long 0, 22 ; lat. 0, 

 8; alt. 0,22 poll. 



A small lenticular smooth species with large auricles. The 

 colour is pale fawn, mottled with red and brown ; there are 

 also white and yellow varieties. Collection of A. Hancock Esq. 



Cullercoats, Great Britain. 



38. P. ORBICULARIS, (pi. XX, f. 231. 232.) 7wb. 



T. rotundata, ineequivalvi, laevi, tenui, sub-eequilaterali ; 



G 



