S T R .E A. 



Species 38. (Fig. a, b. Mus. Taylor). 



OsTii^.v suBTHKiONA. Ost. testd subtrigotid, obtimgd 

 vel mbquadratd, ponderosd, versus umbones sub- 

 angustaid, ad marginem ventralem lata, qvadratd ; 

 margine valide plicato ; valvA inferiori profundd, 

 albido-subviridi, pu/-piireo marginatd, extits nidia- 

 Hm plicatd, fulvo et purpiireo concentrke fusciatd; 

 cardine acuminato, latcribtts prope cardinem crenu- 

 latis. 



The .suBTniGONAL 0.sTn.i';A. Shell subtrigoiuil, oblong 

 or subquadrate, ponderous, rather narrowed 

 toward the umboes, broad at the ventral margin, 

 quadrate; margin strongly plicated, lower valve 

 deep, greenish white, edged with purple, without 

 radiately plicated, concentrically banded witli 

 fawn and purjjlc ; hinge acuminated, sides crenu- 

 lated near the hinge. 



SoWEliBV. 



Hah. Australia. 



The sculpture of this shell is bold and large ; and 

 the square character of the ventral margin is striking. 



Species 31). (:\Ius. Ilanley.) 

 OsTR^A TCLU'A. Ost. tistd tctiiii, ilougato-subovatd, 

 Icevigatd, purpurea, versus margincs pallidd, pi-ope 

 umbonem fascid albd mediand radiatd ; valvuld in- 

 feriori profundd, margine tenvissimo ; intus albi<lo, 

 purpureo tincto ; imprefsione muscvlari parvo, 

 purpurea. 



The tulip OsTP.yEA. Shell thin, elongately-subovate, 

 smooth, purple, pale towards the margins, rayed 

 near the umbo, with a white medial band ; lower 

 valve deep, with very thin margin ; inside whitish 

 tinted with purple ; muscular impression small, 

 purple. 



Lamarck. Anim. sans vert. Ostraia, No. 10. 



OMrcea ^quatorialis, D'Orbigny ? 



Hub. Central America, on Mangroves. 



Allied to Ostrcea Rhizophorm and 0. p(mtsitica, of 



which it may possibly be a variety. 



Species 40. (Fig. ,i, Mus. Taylor ; b, r, Mus. Ilanley.) 



OsTR,EA I'OLiUM. 0.<t. tc.'itd teiiuiusculd, fused aut 

 fusco-purpurcBd, ad Ehizophoras adham-enti per lobis 

 elongalis valimlce inferioris ; valvuld superiori 

 in medio in costd tubceformi elevatd, ad latera 

 divaricatim plicatd ; plicis rotiindis, Imvigatis. 



The leaf Ostr^a. Shell rather thin, brown or 

 browni.sh purple, adhering to mangroves by 

 elongated lobes of the lower valve ; upper valve 

 in the middle elevated into a tube-shaped rib, 

 at the sides divergently ribbed ; ribs rounded, 

 smooth. 



G.MEHN. Syst. Nat. Linn. 



OMrcea sabrella. (test, jun.) Lamarck. 



Ilab. Central America, on roots of mangroves. 



This oyster throws out lobes of its shell to reach 



points of attachment. 



■September, 187L 



