773 



6. Petricola denticulata (pi. clxvi. f. 6, 7), Sowerhy, Pro. 

 Zool. Soc. 1834, p. 47. P. ventricosa, Deshai/es, B. M. 



"Pet. testa oblonga, plioladiformi, extus pallescente, intus ad 

 extremitates fusco-nigricante tincta; antice subrostrata, postice 

 rotuudata; liiiea dorsali rectiuscula, ventrali subprominula, om- 

 nino radiatim sulcata et concentrice striata, striis antice sublamel- 

 losis denticulatis." 



Much narrower tlian P. dadylus, more rostrated in front, with 

 the radiating ribs continued quite to the back. Inside brown at 

 both ends. 



Payti, Peru. Cuming. 



7. Petricola nivea (pi. clxvi. f. 13, 14), Chemn., "Mytilus 

 niveus," Conch, viii. 154. pi. 82. f. 734. P. rugosa, Sowerhy, 

 Pro. Zool. Soc. 1834. p. 47. P. fornicata. Say, Journ. Acad. 

 Nat. Sci. Phil. ii. 314 ? P. tenuis, Soimrhy, Pro. Zool. Soc. 1834, 

 p. 47. P. gibba, Middend. ? 



Pet. testa oblonga, pholadiformi, alba, ventricosa, radiatim cos- 

 tellata, costellis serratis antice paulo, postice multb fortioribus 

 margine ventrali antice rotundato postice subcontracto, cardine 

 dentibus nonnunquam subobsoletis. 



The serrated ribs of this cylindrical species are strongest at the 

 hinder part of the shell, and thinnest in the centre. 



Nicobar, Chemnitz. Chili and Peru, Cuming. 



8. Petricola concinna (pi. clxvi. f. 3), Sowerhy, Pro. Zool. 

 Soc. 1834, p. 46. 



Pet. testa oblonga, pholadiformi, albican te ; concentrice costel- 

 lata; antice rotundata, radiatim sulcata dorso declivi, alterius 

 valvse lamella laevigata ; postice acuminatiuscula, costellis concen- 

 tricis lamellosis confertis. 



Like P. pholadiformls in shape, with radiating serrated ribs in 

 front, and regular concentric lamina?, commencing in the middle 

 and widening at the back. 



Monte Christi ; found in hard clay at low water. Mr. Cuming's 

 collection. 



9. Petricola elegans (pi. clxvi. f. 8), Beshayes {Venempls), 

 Pro. Zool. Soc. 1853. 



V. testa elongata ovali intlata, pallida, radiatim leviter striata, 

 antice subacuta; postice subtruncata; laminis coucentricis antice 

 et in medio, subduplicatis postice tenuibus productioribus ; lunula 

 tumidaj margine dorsali, recti, impressa. 



