S T R iE A. 



Species M. (Fig. <i, li, Mus. Rrit.) 

 OsTR^EA RADIX. Od. tcstd mbcortipressd, tmuiusculd, 

 irregulari, oblongd, radialim plicatd, plicis laxis. 

 rotundatis, cdhido-svhpurpured, vel omnino fused, 

 purpureo vel fiisco lineatim g/rigatd ; valvnlA in- 

 feriori foliaced, foKis exsCanlihus adiuprentibus ar- 

 matd ; valmdd superiori alteram (rquanti. 

 Till-: KOOT OsTRiE.\. Shell siibooinpresseil, rather thin, 

 irregular, oblong, radiately plicated, plaits loo.se, 

 rounded ; purplish white, or brown all over, 

 linearly striped with jmrjjle or brown ; lower valve 

 foliaceous, armed with outstanding adhering folia- 

 tions ; upper valve equalling the other. 



SOWERBY. 



IM>. .' 



I do not find that any author has yet named this 

 species, which appears fairly to merit distinction. Pig. 

 It, however, is not very cliaracteristic, the plaits being 

 nearly obsolete. 



Species :V2. (Mus. D'Orbigny in Brit.) 



OsTR.«!A SPRETA. Ost. testd. sfi,bquadratd, antic'e sub- 

 productd, cuneatd ; margine cardinali anguxto, 

 apicibus acuminatw ; valvidd in/eriori subpro/undd, 

 intils vai-iegatd; valvuld superiori purpureo strigatd, 

 rugosd, versils marginem irregulariter plicatd. 



The .slighted Ostr^a. Shell subquadrate, rather pro- 

 duced and cuneated anteriorly ; hinge margin 



Species SI. (Fig. a, h, Mus. Urit.) 



!.«A MOUDAX. Ost. testd pei-pendicularitcr oblongd, 

 compres.-)d, ad marginem profundi; lohntd, intvs 

 inter lobas acute denticulaiil : valruld inferiori 

 crassd, medio albidd. Umbo inter denticulas dense 

 fuico-purpureo; margine cardinali recto, ad terminos 

 quaJrato ; valmdd guperiori subcinnamoned, pnr- 

 pureo variegntd, valde planulatd. 

 BITING Ostr^a. Shell perpendicularly oblong, 

 compressed, deeply lobed at the margin, acutely 

 denticulated within between the lobes ; lower- 

 valve thick, whitish within, the border between 

 the denticles deep purple-brown ; hinge margin 

 straight, squared at the ends ; upper valve slightly 

 cinnamon-tinted, variegated with purple, very flat. 

 LD. Wilson's Expedition. 

 », California ? 



narrow, apices acunnn 

 deep, variegated witl 

 striped, rough, irregul 

 margin. 

 D'Orbigny. Voy. .Vnu'r. "SU 

 llnh. Kio de .buieirn, P,r;izil 



lowiT v.ilve rathe 

 upper valve ])urpl 

 [ilicated tow.'irds tl: 



A very gi- 



IS species of irregular growth. 



(Mus. Brit.) 



Ostr.-ea Ciiii.okx^is. (>!it. tisfd valde foliaced, elongato- 

 subtrigonA, albidd, iidhs partim viridesccnti, mar- 

 ginibus haud denticulatis, valvuld inferiori alteram, 

 ad margineni superanti, vix profnndd ; valvuld 

 superiori planulatd, sublctvigatd, taxi sqv/imatd 



The Chiloe O.str/ea. Shell very foliaceous, elongated, 

 subtrigonal, whitish, partly greenish within, mar- 

 gins not denticulated ; lower valve exceeding the 

 other at the margin, not very deep; upper valve 

 flattened, rather sinodth. loosely scaled. 



Hub. Chiloe. 



There is truly very little to distinguish this sjieci 

 from the " Xative" variety of our edible oyster. It : 

 however, of thinner growth and more tapering towar 

 the hinge. 

 February, \X~i\- 



