BEAcmoroDA. 



369 



vrith. con^sponding ribs ; hinge-line wide and straight, with a 

 narrow area to each valve ; foramen large, deltidium rudi- 

 mentary ; interior of dorsal valve with one or more prominent, 

 sub-marginal soi:)ta ; loop two or four-lobed, adhering to the 

 septa, and more or less confluent with the valve 



Fig. 162. A. decoUnta, ^p~ ; dorsal valve with the animal, from a specimen dredgPti 

 l)v Professor Forbes in the .^ean. The oral aperture is seen in the centre of tlie 

 disk. 



Animal with oral arms, folded into two or four lobes, united 

 by membrane, forming a brachial disk fringed with long ciiTi; 

 mantle extending to the margins of the valves, closely adherent. 



Distribution, 5 species. North Britain, Madeira, Canaries, 

 Mediterranean. 30 — 105 fathoms. 



Fussily 19 species. Oolite — . Europe. 



Fig. 163. T. radians. Fig. 164. T, Meditcrraneum.* * 



TiiEClDltJM, Defrance. 

 Etymology, Thehidion, a small pouch. 

 Type, T. radians, PL XV., Fig. 11. 

 Shell small, thick, punctate, attached by the beak; hin^o- 



* Dorsal valve with the animal, magnified. Cull. Davidson. 

 11 3 



