15 
que aterrime violacea ; umbonibus brevibus, minimis, oppositis, 
approximatis, apice decorticatis ; valvis tenuibus ; cardine an- 
gusto, inequaliter tridentato; dente antico in utraque valva 
angusto ; dentibus lateralibus brevioribus, angustis, oblique sul- 
parciragons s tmpressione pallii postice leviter inflexa. 
Hab. t 
9. Cyrena 1nquinaTA, Desh. C. festa orbiculato-trigona, tur- 
gida, inflata, subcordiformi, inequilaterali, epidermide squa- 
lide fusca, fuliginosa, dense et irregulariter lamellosa vestita ; 
umbonibus tumidis, profunde erosis; margine superiore antico 
declivi, rectilineo, postico convexiusculo, inferiore subsemicircu- 
lari; valvis solidiusculis, intus albis ; cardine angusto, arcuato, 
tridentato; dentibus inequalibus, brevibus, obliquis, parallelis, 
angustis, parum prominentibus, duobus bifidis ; dentibus latera- 
libus minimis, brevibus, antico prominentiore ; ligamento brevi, 
partim infosso ; impressione pallit prope marginem decurrente. 
Hab. China (rivers). 
10. Cyrena FALLAX, Desh. C. festa ovato-trigona, plus mi- 
nusve tumida, crassa, solida, in medio ventricosa, epidermide 
squalide fuscescente, ferruginea, in junioribus flavescente ves- 
tita, transversim irregulariter striata; latere antico breviore, 
superne fere rectilineo, declivi, rotundato, inferiore margine 
postico superiore recto, declivi; extremitate postica sensim 
attenuata, breviter truncata; area plana, levigata, angulo 
obtusissimo circumscripta; cardine satis lato, dentibus tribus 
inequalibus, in valva dextra crassioribus, majoribus, bilobatis ; 
dente laterali antico compresso, brevi, postico longiore. 
Long. 81 mill., haut. 69, épaiss. 48. 
Hab. Philippine Islands ; Australia (Cuming). 
11. Cyrena consuncta, Desh. C. testa orbiculato-trigona, 
crassa, solida, ventricosa, subequilaterali, utroque latere ob- 
tusa, rotundata, inferne regulariter arcuata, margine antero- 
superiore declivi, rectilineo, postico convexo, epidermide viridi, 
fuscescente, transversim regulariter tenue lamellosa vestita ; um- 
bonibus tumidis, obliquis, brevibus, obtusis, erosis ; ligamento 
brevi, angusto, immerso; valvis intus albis ; dentibus cardinali- 
bus tribus inequalibus, postico valve dextre latiore, inequaliter 
bifido, mediano eminentiore, acuto, profunde bilobato ; dentibus 
lateralibus parvis, distantibus, antico eminentiore, conico, com- 
presso. 
Hab. 2 
12. Cyrena tauta, Desh. C. testa ovato-transversa, subtri- 
gona, inequilaterali, superne inferneque convexiuscula, postice 
subtruncata, antice valde declivi, rectilinea, crassa, solida, in 
medio convexa; epidermide fusca, nitida, tenue trregulariter 
striata; umbonibus depressis, brevibus, apice acutis, approxi- 
matis, sepius erosis; lamina cardinali lata, dentibus cardina- 
