MULLERIA. 



which passes the muscular impression of the mantle, to- 

 wards the anterior part of the shell ; in our specimen the 

 muscular impression of the mantle is irregular and in- 

 distinct. The ligament is rather elongated, external, its 

 posterior termination, however, fills a sinus in the edge 

 of the shell, apparently formed to receive it, and in this 

 respect it approaches very closely to the Naiads, while it 

 differs materially from the Ostrea. The beak is rather 

 pointed, anterior and lateral in our specimen. A dull 

 yellowish brown epidermis covers those parts of the shell 

 which have not been exposed to attrition. 



