61 



pressa, minutissime cancellata, umbonibus acuminatis, margine 

 ventrali denticulate, plerumque inflexo ; auriculis panns, 

 posticis minoribus ; valva sinistra in medio paululum excavata, 

 costis 5, magnis, elevatis, gradatim declinentibus, prope 

 umbones angulatis, prope margimen inflatis ; valva dextra sub- 

 ventricosa, costis 4 magnis, elevatis, latis, rotundatis ; colore 

 pallidissime rufo, maculis rubris parvis, et fuscis radiatis vari- 

 egato; valvee dextrse albo. Long. 1. 10.; lat. 0. 35.; alt. 1. 

 20. poll. 



This shell differs from P. Danicus, in being much narrower, 

 and more elongated towards the umbones; having the margins 

 generally inflected, the ribs larger and deeper, and the 

 upper valve concave. We believe P. flexuosus, figured in the 

 same plate of Poli*s work, to be a variety of this Mediterra- 

 nean species. Sicily. 



48. P. DANicus. (pi. xii. f. 16. and pi. xvii. f. 18/.) 

 Chemn. Conch. 11. t. 207. f- 2043. Including P. Pseudam- 

 usium, Chem. 7. t. 63. f. 601. 602. P. aspersus, Lam. Ostreea 

 hybrida, Gmel. 



T. compressa, sub-circulari,subsequilaterali,l8evi velradiatim 

 obsolete striata; costis septem, latis, pauxillulum elevatis, 

 gradatim declinentibus, angulatis, prope marginem evanidis ; 

 colore palhde rubro, maculis rubris, parvns, numerosis, varie- 

 gato, vel fusco, obsolete maculate. Long. 1. 60. ; lat. 0. 43. ; 

 alt. 1. 60. ; poll. 



A compressed, somewhat equilateral species. The general 

 surface is smooth, obsoletely striated, with seven ver}'- slightly 

 raised angiilar ribs, which are fainter near the margins. The 

 colour is pale red, sprinkled with minute irregular spots of 

 darker red. A variety occurs of a dull brown colour. 



Scotland, Denmark ? 



49. P. DiSTANS. (pi. xiii. f. 46, and pi. xviii. f. 182.) 

 Lam. Anim. s. Vert. vi. p. 169. 



T. sub-ovali, sub-compressa, sub-eequilaterali, radiatim 

 striata ; cardine oblique plicato ; auriculis sub-cequalibus, 

 anticis ad basin emarginatis ; costis decern, rotundatis, elevatis, 

 crassis ; colore griseo, macuHs et fasciis fuscis, nigricantibus 

 variegato ; intus fusco. Long. 1. 54.; lat. 0. 61.; alt. 1. 87-; 

 poll. 



Rather oval, rather flattened, nearly equilateral, radiately 

 striated; hinge ol^liquely plicated; auricles nearly equal, 

 narrowed at the base ; the ribs, 10 in number, are rounded, 

 elevated and thick ; the colour is a light cream, with bands 

 and spots of a very dark brown, inside brown. Specimens 



