l/i 



pedicle; valves sometimes moveable and distant, 

 sometimes soldered together, lined internally by the 

 mantle. 



ORDER SESSILIA. 



Affixed and not pedunculated : aperture superior and 

 anterior. 



GENUS CORONULA. 



Sessile, suborbicular, seemingly one entire piece, conoid 

 or refuse conical, truncated at the extremities; 

 substance thick, hollowed interiorly by radiating 

 cells : operculum with four obtuse valves. 



C. DIADEMA. Lam. \.-Bl. t. 86./. 4- LEPAS D. 

 Lin.Ch.f. 843. List. t. 46. f. 288. Born, t. I. 

 y. 5. 6. Wood, G. C. t. 4. Da. Cos. t. 7. f. 2. 

 Don.t.6Q. f. 1. 2.Turt.D.p.75.D.p.24.~~ 

 BALANUS. D. Mont. p. 13. Brug. p. 171. Sub- 

 compressed, hemispheric, dirty white, with twelve com- 

 partments, six depressed, flat, and striated transversely, 

 the others, which are alternate, are prominent with lour 

 five or six elevated longitudinal ridges and transverse 

 striae ; at the top is a deep cavity, funnel shaped, hex- 

 agonal within, at the bottom of which is the aperture, 

 the ribs are also furnished with divisions or cells in a 

 radiated manner and lined with a coriaceous membrane. 

 Diam. 2 to 3. Rare, except in Scotland and its isles* 





