J1825.] arranged in Natural Families. ' ^ 103 



of the operculum none; operculum convex, two-valved, the 

 ventral and posterior valve of each side being soldered together. 



D. Linnsei, nob, Esper Zooph, Madrep, t. 85. 



Obs. Linnaeus describes this species as part of his M«<frejoom 

 'Polygama, and appears to take the name from his behef that the 

 coral was inhabited by two kinds of animals. — (See Lu/. Sy^. 

 Nat. 1275 ; Am, Acad. iv. 258, t. 3, f. 15 ; Esper. Zooph. i. 29 ; 

 Boddaert, Elench. Zool. 324.) 



3. Megatrema, Leach, without character. 



Valves of the body of the shell, four, soldered together; sheath 

 of the operculum nearly as long as the valves; operculum 

 conical, four-valved, valves subtriangular. 



fSupportof the valves immersed. Valves finely striated. 

 . M. Stokesii, Grai/. Mas. Brit, on Fungia. 



i^t Valves convex ; support of the valves conical exserted ; 

 Adna, Leach, no character. 



M.A. Anglica; valves and support radiately grooved, and 

 concentrically striated ; Devonshire, Mas. Brit, on a new species 

 oi Caryophyllia, 



4. Creusia, Leach (n. 14). 



Valves of the body of the shell 4, distinct ; sheath of the oper- 

 culum nearly as long as the valves ; operculum conical, four- 

 valved, valves triangular. 



-^Base convex, prominent, sitting on the coral ; shell convex. : :r 



C. spinulosa, Leach. Mas. Brit. 



Dr. Leach describes the valves of the operculum as soldered 

 two and two, but they are not so in the Museum specimens. 



ffBase sunk in the coral; body of the shell nearly Jiat. 



C. Childreni, nob. Mas. Brit. 



^^ Shelly valves of the body, six. Living in or on the surface 

 of horny or barked zoophytes. • 



5. CoNOPLEA, Say (n. 16). 



Body short ; valves six, elongate, distinct, truncated ; ven- 

 tral, dorsal and lateral dorsal pair large; lateral ventral pair 

 small ; operculum conical pointed, four-valved. The base elon- 

 gate keeled. Attached to the stems of GorgonicK. 



1. C. elongata. Say. The base elongated behind. N. Ame- 

 rica. B. galeatus, Gmelin. 



2. C. ovata, nob. The base ovate. Africa. 



6. Ac A ST A, Leach (n. 13). 



Globular ; valves six distinct^ long triangular ; apex acute ; 

 the ventral, dorsal, and lateral dorsal pair, large ; the lateral 

 ventral pair, small; operculum conical, acute, four-valved. Base 

 hemispherical. Imbedded in sponges. 



1. A. Montagui, Leach. Lepas spongiosa, Montague. 



2; A. laevigata, Gray, Shell subglobular, yellow, unarmed. 

 Valves fiuely concentrically striated ; the Trppics. 



