176 



CL^SS. III. 



ELETOBRANCHIA Mke. (Lamellibranchiala 

 Blainv.; Polecypoda Goldf.; Conchifera Lam.) 



ORD. I. OSTRACEA Mke. 

 ■* SUBORD. I. MONOMYA Mke. 



FAM. I. OSTRACEA Mke. 



LXm. PLACUNANOMIA W. J. Broderip. 



Testa adhaei-ens, subaequivalvis, irregularis, compla- 

 nata, marginem versus plicata, interne vitrea. Cardo in- 

 ternus, dentibus duobus elongatis, crassis, subcm'vis, diva- 

 ricatis, basi convergentibus in valva infcriore, sulcis duo- 

 bus ligamentiferis in superiore. Valva inferior cardinem 

 versus supcrficialiter iiTegulariter externe fissurata, organo 

 adhaesionis subosseo inter testae laminas inserto et externe 

 fissuram implente. Impressio muscularis in utraqiie valva 

 subcentralis. In valva superior« organi adhaesionis impres- 

 sio superaddita. 



Genus ostreae L., plicatulae Lam., placunae Brug., ac 

 anomiae L, aliquatenus affine et intermedium. 



Proceedings. 1832. p. 28. 



1. Placunanomia Cumingii TF. J. Bro- 



derip. 



Pl. testa subrotunda, obscure argenteo-albida, compla- 

 nata; margine plicato, plicis maximis. 



Long. 2| poll , lat. Y^^ poll., alt. 2^ poll. 



Legit H. Cuming ad oras Americae centralis (Gulf of 

 Dulce, province of Costa Rico). 



Proceedings. 1832. p. 29. 



2. Placunanomia rudis TP. J. Broderip. 



Pl. testa sordide alba, crassa, concentrice irregulariter 

 corrugata, intus nitide polita. 



Long. \\ poll., lat. |- polL, alt. 1| poll. 

 Ostreae edulis L. speciem refert. 



Legit 



