Myochama.—Cleidotherus. 97 
MyocHAMA ANOMIOIDES. 
Tas. Supp. xt. f. 1, 2, 3, 4. 
M. testd rosed, tenui, fragili, costis prominentibus radiantibus dichoto- 
mis ; valvd liberd valde converd ; wmbone extra apicem valve altere 
producto ; epidermide tenut, pellucidd ; long. 13, lat. , alt. 3. 
Shell rose-coloured, thin, fragile, ornamented by prominent radiating 
dichotomous ribs. Free valve extremely convex, the umbo projecting 
beyond the apex of the other. Epidermis thin and transparent. 
The shell described above adheres to a smooth species of Pectunculus ; 
some specimens are attached to Trigonia* pectinata, in which case the 
natural ribs are crossed by others still more prominent, corresponding 
with those of the shell on which they have grown, 
CLEIDOTHERUS.t 
Testa sulmargaritacea, inequivalvis, adherens. Cardo, dente conico 
in valvd liberd, in fossulam alterius valve inserto, claviculd testaced 
elongatd recurvd, cartilagine connexd, et in cicatrict profundd infra 
utrumque umbonem insertd. Impressiones musculares, in utrdque 
valvd due, laterales, antica prelonga, postica sub-orbicularis. Im- 
pressio muscularis palliz integra. Ligamentum externum. 
Shell somewhat pearly, inequivalve, adhering. Hinge with a small 
conical tooth in the free valve, fitting into a corresponding pit in the 
attached valve. A testaceous, elongated, curved clavicle, connected by 
cartilage, is inserted in a deep cicatrix under each umbo. Muscular 
impressions two, lateral, the anterior lingulate, the posterior suborbicu- 
lar. Muscular impression of the mantle entire. Ligament external.t 
* It may not be thought irrelevant to mention that Trigonia must be re- 
moved from the situation Lamarck has given it, between the Arcacee and 
Naiades, to the Cardiacee ; having seen the living animal, I am convinced it 
bears the nearest affinity to that family. 
+ From the Clavicle in the hinge. 
t Since this Article was sent to press, it has been ascertained that De Roissy 
has named and characterized this remarkable genus, though evidently from 
incomplete specimens, He has called it in French “ Camostrée’’ a name so 
Vou. V. G 
