186 NEW-YORK FAUNA MOLLUSCA. 



M. carolinensis. (Conrad, Jour. Ac. Sc. Vol. 7, p. 244, pi. 20. fig. 6 ) Shell dilated in the middle: 

 disks with very numerous radiating strife ; lower margin rounded, and beautifully crenulale. Colon 

 greenish yellow ; within yellowish, spotted with purple. Crenella ? Charleston, S. C. 



M. amerkana. (Leach, ZooI. Misc. Vol. 2, pi. 72, fig. 1. Say, Ac. Sc. Vol. 2, p. 265.) Oblong_ 

 Hinge-margin elevated in a right line from the beak to the alaled angle, from which it declines in 

 a right line nearly to an equal distance; alar projection rounded : anterior margin short and small 

 basal margin slightly contracted in the middle. Coloi : Epidermis transversely wrinkled, light 

 brown; the raised oblique portion of the shell yellowish-white: cortex with membranous scales 

 and filaments. Length. 0-6; breadth, 1'2. Southern Coast. 



M. castmiea. (Say, Ac. Sc. Vol. 2, p. 26G ) Transversely oblong, suboval. Hinge-margin elevated 

 in a right line from the beak to the alar angle, from which it descends in a slightly arcuated line; 

 alar angle rounded: anterior margin rounded at the tip ; posterior margin rather large : base with 

 a slight contraction before the middle. Color: epidermis chesnut ; within bluish. Length, O-S; 

 breadth, l-l. Southern Coast. 



GENUS CRENELLA. Brown. 



Oblong-ovate, subequilateral, ventricose. Beaks obtuse, slightly turned to one side. Hinge 

 without teeth, but with a flattened slightly crenated plate in each valve ; the right valve 

 witli a triangular horizontal projecting reflexed plate, and the left one with an oblique plate, 

 both of which are slightly crenated. 



Crenella decussata. 



PLATE XXII. FIG. 246. 



(STATE COLLECTION.) 



Mylilus decussalus. Laskey & MoNTAGn, Mem. Wer. Soc. Vol. I. 

 Crmdia tUiptka. Brown, Couch. Illus. pi. 31, figs. 12 - 14. 

 Modiala glandule. Totten, Am. Jour. Vol.26, p. 367. pi. fig. 3. 

 M. id. Gould, luvertebrsta of Mass. p. 131, fig. 87. 



Description. Shell small, thin, oval, turgid, inequilateral, not gaping. Valves concentri- 

 cally wrinkled and beautifully striated, with numerous small rounded ribs, radiating in all 

 directions from the apex to the margins ; cavity of the valves profound. Beaks distinct, re- 

 curved, not in contact, often decorticated : the entire margin minutely crenulated. 



Color. Epidermis dull waxen yellow ; within bluish white, somewliat pearly. 



Leng, 0-2 -0-45. Width, 0" 15 - 0-35. 



This little shell was first discovered by Col. Totten at Provincetown harbor, Mass., and, 

 according to Dr. Gould, is one of the most common shells found in the stomachs of fishes on 

 that coast. Under the latter circumstance, it will probably be detected on the coast of this 

 State. The place of the genus is uncertain : it should probably be arranged near Anatina. 



