222 DESCRIPTION OF 



epidermis yellow, inclining to greenish brown, smooth and shining; cardinal 

 teeth long and compressed; lateral teeth long and somewhat curved; anterior 

 cicatrices confluent; posterior cicatrices confluent; dorsal cicatrices placed on 

 the centre of the cavity of the beaks; cavity of the shell rather shallow; cavity 

 of the beaks shallow and subangular; nacre pearly white and very iridescent. 



Remarks. — This species in outline resembles the U.pictorum, Lam. and Unio 

 Corrianus, nobis. It was sent to me from Bremen by Dr. Von den Busch, who 

 thinks it came from Java, but is not sure of its habitat. In the two specimens 

 before me the rays on the posterior portion are very distinct. 



Margaritana Vondenbuschiana. Plate 18, Fig. 39. 



Testa obovatd, compressd, inaquilaterali; valvulis tenuibus; natibus suhprominentibus ; epidermide 

 luteo-fuscd; dentibus cardinalibus parvis, tuberculatis ; margaritd albd et iridescente. 



Shell obovate, compressed, inequilateral; valves thin; beaks somewhat prominent; epidermis yellowish- 

 brown; cardinal teeth small, tuberculate; nacre white and iridescent. 



Hab. Java. G. Von den Busch, M. D. 



My Cabinet, and Cabinet of Dr. Von den Busch of Bremen. 

 Diam. .8, Length 1.8, Breadth 2.8 inches. 



Shell obovate, compressed, inequilateral; substance of the shell thin; beaks 

 somewhat prominent; ligament long and thin ; epidermis yellow, brown, obscure- 

 ly rayed, darker on the posterior slope and lighter towards the basal margin ; 

 cardinal teeth small, consisting of an irregular tubercle; anterior cicatrices con- 

 fluent; posterior cicatrices confluent; dorsal cicatrices placed in a row across 

 the cavity of the beaks; cavity of the shell shallow; cavity of the beaks very 

 small ; nacre white and iridescent. 



Remarks. — The form of the teeth in this shell places it near to the genus 

 Ajiodonta. The enlargement of this part is greater than in the Alasmodonta 

 edentula, Say, {Anodon areolatus, Swainson,) which I have, in my synopsis, 

 placed with the Anodontce. It, in fact, falls into that division which d'Orbigny 

 has made under the name of Monocondylcea, and is somewhat like his species 

 fossiculifera. I name it after Dr. Von den Busch, to whose kindness I am 

 indebted for the specimen now described. 



