194 NEW-YORK FAUNA — MOLLUSCA. 



Unio NOVI-EBORACI. 



PLATE XX. FIG. 240. 

 (CABINET OP DRS. JAY AND BUDD.) 

 Unio nmi-eboraci. Lia, Tran*. Am. Phil. Soc. Vol. 6, p. 104, pi. 24, 'fig. 114. 



Description. Shell elliptical, somewhat compressed. Substance of the shell rather thick ; 

 thinner on the posterior portion. Beaks somewhat prominent, and minutely undulated at the 

 tip. Cardinal teeth large, erect, and deeply cleft in the left valve ; lateral teeth long, straight, 

 and separated from the cardinal teeth. Anterior cicatrices distinct ; posterior confluent : dor- 

 sal cicatrices placed in the centre of the cavity of the beaks. Cavity of the shell shallow ; of 

 the beaks subangular and shallow. 



Color. Epidermis yellow, with green rays nearly over the whole disk ; nacre white, and 

 very iridescent on the posterior portion. 



Length, l'l. "Width, 2*2. Diameter, 0*7. 



This species, according to Mr. Lea, whose description I have copied, is closely allied to 

 U. iris. It is, however, a thicker shell, more angular behind, and not quite so transverse ; 

 the epidermis is also more yellow. Mr. Lea's specimens were from Oak-orchard creek, 

 Orleans county. In its form it much resembles the U. pictorum of Europe, but is more 

 robust. Its teeth distinguish it sufficiently from U. radiatus. I am indebted to Dr. Budd 

 for a specimen from another locality, which is one-third larger than that described by Mr. 

 Lea. 



Unio tappanianus. 



PLATE XX. FIG. 848. 



(STATE COLLECTION.) 



Unio tappanianus. Lea, Trans. Am. Phil. Soc. Vol. 6, p. 62, pi. 17, fig. 55. ' 



Description. Shell rather thin, somewhat compressed, regularly rounded in front, dilated 

 behind, subalated above. Posterior slope oblique (in some specimens nearly straight) : basal 

 margin slightly arcuate. Beaks in the anterior third of the shell, slightly prominent, with 

 double undulations. Cardinal teeth small, wide ; that of the left valve double, but this is 

 not constantly very distinct (in the largest specimens it is single) ; lateral teeth small, simple, 

 linear. Surface with three or more strong concentric folds, which are most robust on the 

 anterior portion, and appear on the inner surface. Within, the cavity is capacious ; under 

 the beaks, angular. 



Color, varying from dusky brown to olive brown, with faint narrow greenish radiations, 

 most conspicuous behind. 



Length, 0'8 - 1 -2. Transverse diameter, 1 «4 - 2*2. 



