5g DESCRIPTIONS OF 



little prominent, undulate at the tips ; epidermis yellowish and striate ; nacre either 

 purple or white and very iridescent. 



Anodonta gracilis, Lea. Proc. Zool. Soc. Lond., ISfiO, p. 1!I7. 

 Hub. — Dingle, Isle of Panay. H. Cuming. 

 My cabinet and cabinet of Mr. Cuming. 

 Diam. 1, Length IT, Breadth 3-4 inches. 



Shell smooth, transverse, subcylindrical, very inequilateral, rounded behind, with 

 a broad internal margin ; substance of the shell thin, slightly thicker before ; beaks a 

 little prominent, undulate at the tips; ligament long, somewhat thick and dark 

 brown; epidermis yellowish, sometimes inclining to brown, sometimes to green, 

 obscurely radiate, with distant lines of growth, striate ; umbonial slope slightly raised 

 and rounded ; posterior slope raised into a keel, thickly striate and darker in color; 

 anterior cicatrices distinct and slightly impressed ; posterior cicatrices confluent and 

 faintly impressed ; dorsal cicatrices placed on the upper and inner side of the cavity of 

 the beaks directly under the point of the beak ; cavity of the shell rather deep and 

 wide ; cavity of the beaks shallow and rounded ; nacre either purple or white and 

 very iridescent. 



BemarJis. — This species is more cylindrical than is usual with the Anodonta, and 

 differs from the other species taken by Mr. Cuming in this character ; it is rounded 

 anteriorly, and is subangular posteriorly. The dorsal margin is nearly straight, the 

 basal margin is slightly emarginate, the disk being disposed to be flattish. In the 

 specimens under examination, the beaks are all more or less eroded, but in the 

 youngest there are slight indications of undulations. 



The four species herein described from the Philippines are remarkable in the char- 

 acter of the dorsal line, which rises immediately under the margin into a dentoid line 

 somewhat lamellar, and approaching in its character the more distinct tooth of the 

 genus Dipsas, Leach. In the younger specimens this is much more distinctly 

 marked, and in the older it becomes obsolete. This group of Anodontce, having this 

 dentoid 'character, would seem to form a natural connection on one side with the genus 

 Dipsas and on the other with the genus Unio, connecting with U. Bengalensis brought 

 by Dr. Burrough from India, and described by me in the Trans. Am. Phil. Soc. 

 vol. vi. pi. 2, fig. 3. This remarkable form of tooth, if it may be so called, is joeculiar. 

 to that part of the world, so far as my observation extends ; for among the numerous 

 species examined by me from Europe, Africa and America, Soutli as well as North, I 

 have never met with this character developed as in those alluded to above. 



Unio Cumingii. PI. 35, fig. 120. 



Testa bialata, plicata, triangulari, valde coinpressa, postice angulata, valdc insquilatcrali ; ala posteriori 

 elevata, acuminata, margine crenulata : valvulis subtenuibus antfe et post nates connatis ; natibu.s ct 



