G6 



Var. 1 . Brownish red with white striae, from CaUfornia. 

 Var. 2. Variegated with brown and white patches, from Isl. 

 Plata, East Cohmibia. Var. 3. A more depressed shell, of a 

 bright orange colour, from Tehuantepec Bay, Mexico. The 

 examination of a number of specimens has led me rather to 

 consider this proposed sjDCcies as only presenting a variation of 

 P. nodosus, in which the knobs are not so large or conspicuous. 



62. P. NODOSUS. (pi. XV. f. 115 pi. xvii. f. 147.) Linn. 

 Syst. Nat. p. 1145, Ostr. decemradiata, Gmel? Pecten cor- 

 allinus, D'Argenville. 



T. rotundata, ventricosa, sub-sequilaterali, Eequivalvi, radia- 

 tim sulcata : auriculis ina!quali1)us, sulcatis; anticis majoribus, 

 ad basin emarginatis : cardine plicato : costis novera, crassis, 

 nodulos rotundos excavatos ferentibus, alternis minoril)us ; 

 interne duplicatis, ad marginem dentatis : long. 5. 20; lat. 1. 

 50. ; alt. 5. poll. 



This well known species, which has large knobs on the ribs, 

 is generally of a reddish brown colour, but it occurs also of a 

 bright orange. The auricles are unequal, the hinge plicated 

 and the whole surface roughly sulcated. 



Brazil and Isle of France. 



63. P. Miiscosus. (pi. xix. f. 225.) Wood Suppl. Ind. Test. 

 T. sub-quadrata, ventricosissima, eequilaterali, sequivalvi 



scabra; auriculis ieenqualibus, elongato-acutis, scabroso- 

 sulcatis, basin emarginatis, anticis longioribus ; umbonibus 

 prominentibus : costis 18 scabris, sub-angulatis, ad angula 

 spinas breves rectas ferentibus ; ad marginem dsntatis : colore 

 fusco rufescente, intus fulvo. Long. 1. 20.; lat. 0. 80.; alt. 

 1. 30.; poll. 



Ventricose, equilateral, equivalve, rough ; with elongated, 

 unequal ears, and IS ribs, which have small, erect spines on 

 their angles : colour reddish brown. The only two specimens 

 we have seen are in Mr. Cuming's cabinet. 



64. P. RUGOsus. (ph xix. f. 226.) Nobis. Zool. Proc. 1842. 

 T. ovali, ventricosa, crassa, scabra, sequivalvi, sub-sequi- 

 laterali : auriculis insequalibus, scabroso-sulcatis ; posticis 

 minoribus ; anticis basin emarginatis : costis 20, elevatis, 

 squamis annulatis, angulis serratis. Interstitiis Isevibus. 

 Colore, pallide fulvo, maculis obscuris, fuscis, variegato. Long. 

 1. 12.; lat. 0. 55.; alt. 1. 25.; poll. 



Oval, ventricose, thick, rough, equivalve, nearly equilateral, 

 ears unequal, roughly grooved ; ribs 20, elevated, imdercut, 

 with numerous small annulated scales, and serrated edges. 



