P E T R I C L A. 



Plate II. 



Species 8. (Fig. a, b, Mus. Brit.) 



Petricol.\ nivea. Pet. testd oblomjd, inflata, pholadi- 

 /oi-mi, anticl-brevi, rotunda, radiatim striata ; postice 

 elumjatd, snbattennatd, perobiii/iie angulatd, post 

 unguium costis crebris, amitis, radiatd, ad tenninum 

 amjuste truncatd, denti.cidatd. 



The snowv Petuicola. Sliell oblong, inflated, pholas- 

 shaped, anteriorly short, round, radiately striated ; 

 posteriorly elongated, slightly attenuated, very 

 obliquely angular, rayed behind the angle with 

 sharp, close rib.s, narrowly truncated at the end, 

 denticulated. 



Chemxitz (Mytilus). Conch., vol. vii. PL LXXXII. 

 f. 734. 



Petricola rujosa, Sowerby. 



Petricola fornicata, Say. 



Petricola tennis, Sowerby. 



Petricola gibba, Middendorf ? 



Ilab. Nicobar (Ch.), Chili and Peru (Cum.). 



Species 9. (Fig- a, b, Mus. Sowerby.) 



Petricola denticulata. Pet. testd pholadiformi, 

 elongatd, antice liianii, acuminata, ad mai-gines 

 acclici et declivi, costis depressis crenatis radiatd ; 

 postice radiatim striatd, suhacuminatd ; intils ad 

 terminos et prope margincm ventralem castaned. 



The denticulated Petuicola. Shell pholas-shaped, 

 elongated, anteriorly gaping, acuminated, sloped 

 upwards and downwards at the margins, rayed 

 with depressed crenatcd ribs ; posteriorly radiately 

 striated, rather acuminated; chestnut within, at 

 the ends and near the ventral margin. 



SowEi!BY. Proc. Zool. Soc, liSo4. 



Hab. Payti, Peru. ■ 

 This species is eve 



Pdricola Pholadifo 



acuminated. 



e pholas-like in form than 

 liavini; the anterior end 



(Sjiecies 10. Mus. Brit.) 



Petuicola inteuta. P,t. testd elongatd, pholadiformi, 

 antiiv hnri, rotundd, costis (hpresfis crcmdatis 

 radiatd; postice subangulatd, anil angiihua de- 

 pressd, ronlractd, post anguhiiii cn^fis niimerosis, 

 subacutis radiatd, ad terminvm svbrotundd. 

 The uncertain Petricola. Shell elongated, pholas- 

 shaped, anteriorly short, rounded in front, rayed 

 with depressed ribs ; posteriorly subangular, de- 

 pressed, contracted in front of the angle, rayed 

 behind the angle with numerous rather sharp 

 ribs, somewhat rounded at the end. 

 SowEitiiv. 



llab. ? 



I cannot identify the specimens of this shell in the 

 British Museum with Petricola niveus. The latter 

 seems to bo characterized by sharp-edged ridges at the 

 posterior end, wliile in the former the posterior ribs 

 are more decumbent, and less distinct from tlie structure 

 of oth(_-r iiarts. 



Species 11. (Fig. a, b, Mus. So\veii>y.) 

 Petuicola lithopiiaga. Pet. testd brevi, subcuneiformi, 

 radiatim striatd, stiiis posferioribus majoribus ; 

 antice infiatd, rotundatd, brevissimd ; postice sub- 

 attenuatd, ad terminum phisminnsre truncatd. 

 The stone-eating Peteicola. Shell short, rather 

 cuneiform, radiately striated, the posterior stri» 

 the larger; anteriorly inflated, rounded, very 

 short ; posteriorly rather attenuated, more or less 

 truncated at the end. 



Retzius (Venus). Linna?ar 

 Pholas striata, Lamarck. 

 J/'/a decussata, Turton. 

 Pholas costellata, Lamarck. 

 Pholas roCiUaria, Lamarck. 



Transactions of Ti 



November, 1871. 



