P E T R I C L a. 



Species 10. (Mas. Brit.) 



PETniCol.A IU-1'.IGINOSA. I'ct. tcsht hnui, vivlareo- 

 ruliesrenti, subrhomhoidea, omninn (/inin'culim 

 striata ; latere antico breviil^culc, djliijiir siih- 

 truncalo ; umbonibus promineidibus, inanjiiic 

 dorsali subdeclivi; latere postico oblique aiKjutato, 

 ad marginem ventralem acuminato. 



The rubv-coi.ouhed Petimcoi..^. Shell thin, reddish- 

 violet, rather rhomboidal, everywhere divergently 

 striated; anterior side rather short, obliquely sonie- 

 wliat trunciited ; iniiboes prominent, dorsal margin 

 a little sloped ; posterior side obliquely angular, 

 acuminated at the ventral margin. 



Adams and Akgas (Narinia). Proc. Zoul. Soc. 



Hab. ? 



Species 17. (Mus. Ilanley.) 

 PetricoLA BICOLOR. Pet. ttda ovatd, tcimi, radiatim 

 minute striata, utriiique liianii, anticc rntundali'i, 

 hrevi ; postice oblique mhattenuata, riinculd trijund 

 fused pod angulum pictd. 

 The two-coloured Petricola. Shell ovate, thin, 

 radiately minutely striated, gajiing at each end, 

 anteriorly rounded, short; posteriorly a little 

 attenuated, painted with a trigonal patch of 

 brown. 

 SowERur. Thesaurus Couchyliorum, Petricola, i". 22. 



Hab. ? 



Of the same form, and belong to the same group as 

 Petricola lithophaga, but equally striated, and present- 

 ing a triangiilar patch of colour on one side, a very 

 unusual thing in the genus. 



Species 18. (Mus. ? copied.) 



Petricola seiiilailell,\ta. Pet. testa pared, sub- 

 cuneatd, brevi ; antice concentrice lemiter striata; 

 postice angulatd, post angulum laminis prominenii- 

 hus exfoliatd ; margine dorsali decliui ; margine 

 ventrali injiato. 



Novembe 



The half-laminated Petricola. Shell small, rather 

 cuneated, short ; anteriorly concentrically finely 

 striated ; posteriorly angular, exfoliated behind the 

 angle with prominent laminre ; dorsal margin 

 sloped ; ventral margin inflated. 



Lamarck. Anim. .sans Vert. Petricola, No. 3. 



Hab. Rochelle. 



The laminae on the hinder part will prevent this 

 species being confounded with Petricola lithophaga, 

 which it otherwise resemhles. 



Species 19. (Mus. Sowerby.) 



Petricola .squistriata. Pet. testa ohlongd, pholadi- 

 J'ormi, striis radiantibus numerosis crenulalis, 

 cequalibus, et striis concentricis crenulalis, minute 

 cancellatd, postice intus exlusque maculd juscd 

 trigmid pictd ; latere antico breviiisculo, rotunda ; 

 medio valdi; injiato ; latere postico subattenuato, 

 oblique subtruncato ; margine dorsali excavato. 



The EQUAL-STRI.A.TED Petricola. Shell oblong, pholas- 

 shaped, minutely cancellated with numerous 

 crenulated, equal, radiating strise, painted pos- 

 teriorly inside and out with a triangular patch of 

 brown; anterior side rather short, rounded; middle 

 much inflated ; posterior side rather attenuated, 

 obliquely subtruncated ; dorsal margin excavated. 



Sowerby. 



Hah. ? 



Diflering from Petricola denticulata in the rounded 



anterior side and equal decussation. 



Species 20. (Fig. a, b, Mus. Sowerby.) 

 Peteicola R0BU.STA. Pet. tcstd globoso-cuneatd, extiis 

 subcceruled, inliis fusco-nigriscenti ; latere antico 

 valde injiato, rotundo, brevi, liris acutis nu7nerosis 

 radiato ; latere postico attenuato, angustato, sub- 

 an.gulnto, ante angulum depresso, contracto, post 

 angulum acute et conspicue costato, ad terminuiri, 

 truncalo; umbonibus elcvatis, margine dorsali valdi 

 dcclivi. 



r, 1871. 



