1240 Dir-F.ODON 



DiPLODON suAViDicus (Lea). 



"Shell smooth, oblong, somewhat compressed, very inequi- 

 lateral, rounded before and truncate behind, dorsal and basal 

 lines nearly parallel : swollen before the umbonal slope and 

 flattened at the side ; beaks a little prominent, with rather short 

 divergent and re-entering ribs at the apex ; ligament short and 

 thin ; epidermis yellowish-olive, minutely striate, apparently 

 without rays; umbonal slope subangular ; posterior slope raised 

 nearly into a wing : cardinal teeth small, compressed, crenu- 

 late, oblique and double in both valves; lateral teeth long, 

 lamellar, single in The right and double in the left valve ; an- 

 terior cicatrices confluent ; posterior cicatrices confluent ; dor- 

 sal cicatrices placed in the centre of the cavity of the beaks ; 

 cavity of rhe shell rather deep and rounded ; cavity of the 

 beaks rather shallow and angular ; nacre bluish-white and very 

 iridescent. 



Length .8. height .6. diam. .4 in." (Lea). 



Amazon. 

 Unio suaz'idiciis Le\, Pr. Ac. N. Sci. Phila.. A^ITL 1856, p. ()5 ; 



Obs., VL T857, p. 29, pi. XXIX. fig. 24: Jl. Ac. N. Sci. Phila., 



in, 1858, p. 309, pi. XXIX, fig. 24. 

 Maj-garon fUiiio) siiavidiciis LiiA, Syn.. 1870, p. 54. 

 Diplodon siiaiidicus Simpson, Syn., 1900, p. 876. 



"A single small specimen of this species, evidently quite 

 young. I should suppose about one-fourth growni. The above 

 diagnosis, therefore, may be found to be, in many respects, 

 incorrect, when mature individuals shall be examined. The 

 oblong outline of this shell is remarkabl}^ regular. The cost?e 

 of the beaks are smaller on the posterior and anterior slopes 

 and several of them form re-entering angles on the posterior 

 slope and on the sides'. This species has some afiinity to clior- 

 ruanus d'Orb., but dififers in being more oblong, in having 

 smaller costre on the beaks and in having the posterior slope 

 m.ore elevated." 



DiPLODOM p.ROWNii (Lea). 



Shell small, obovate, compressed, solid, inequilateral, with 

 low, flat, strongly radially ribbed beaks ; posterior ridge low 

 but well defined, ending in a blunt point behind about on the 



