326 PROCEEDINGS OP THE ACADEMY OF 



Cucullcea Lam. 



C. vulgaris Morton. Synopsis, p. 64, pi. 3, fig. 8, and pi. 13, f. 5. 

 Under this name have been confounded several species, found in New Jersey. 

 Having the good fortune to have access to Dr. Morton's types, I shall endeavor 

 to separate them, a task which would be almost impossible, with only the 

 meagre description and worse figures, given in the synopsis. The true 

 C. vulgaris is characterized as follows : 



Shell gibbous, sub-triangular. Beaks anterior, prominent, remote. Hinge 

 line short, straight externally, internally curved; teeth? Buccal margin 

 broadly rounded, basal nearly straight; posterior angle produced. Umbonal 

 ridge prominent, subangular; umbonal slopes almost at a right angle with 

 the rest of the surface. Surface marked by distinct, irregular, concentric 

 lines. Area impressed and marked by five or six angular lines. Muscular 

 scars rather small. Pallial line very distinct. 



The most obvious distinguishing characters of this species are the prominent, 

 remote beaks, placed almost at the anterior extremity. 



There is another form found with this, probably a variety, in which the 

 umbonal ridge, iustead of being straight, as in the typical specimens, is dis- 

 tinctly convex in the middle. 



C. neglecta. Shell subquadrate, more compressed than the preceding 

 species. Beaks small, incurved, placed near each other, and almost one-third 

 of the distance from the anterior end. Buccal extremity prominent, rounded. 

 Anal margin nearly parallel with the buccal, and much less produced than in 

 C. vulgaris. Basal margin broadly and pretty regularly convex. Area small, 

 narrow. Internal plate long and narrow. Surface marked by numerous, rather 

 small, radiating lines. 



Length, 1 in. Width, 1-3 in. Diameter, -8 in. 

 Found abundantly with the preceding. I have only seen casts. 

 This species approaches most nearly C. Mailleana [Area id. d'Orb.,) but is 

 much less ventricose, and the beaks are not half the distance apart. There is 

 little or no resemblance between it and C. vulgaris. 



C. transversa. Shell very gibbous. Beaks large, prominent and very 

 far apart, placed about a third of the distance from the buccal end. Area 

 broad and very long. Posterior-basal angle prominent. Internal plate low and 

 broad. Hinge nearly straight. Surface marked by numerous radiating lines. 

 Length, 1-4 in. Width, 1'8 in. Transverse diameter, 1.5 in. 

 One specimen in the collection of the Academy, presented by Mr. Harris, 

 probably from Arnejtown, N. J. 



From the preceding species, this can be distinguished by the much deeper 

 valves, more remote and prominent beaks and loog hinge area. It is the most 

 convex species in New Jersey, being more so, in proportion to its size, than 

 C. antrosa Morton. The form will distinguish it from that species. It resembles 

 somewhat C. fibrosa Lam., but is more convex on the basal margin, the beaks 

 are larger and more remote, and the whole shell is somewhat more oblique. 

 The hinge is longer than that species, as is also the width of the shell from 

 buccal to anal margins. From Area quindecemradiata, it can be distinguished 

 by having probably twice the number of ribs, and by being more convex. 



Lithophagus Muhlf. 1811. 



Lithodomas Cuv. 1817. 



L. Ripleyanus . Tube subcylindrical, nearly straight, gradually taper- 

 ing, broadest on the dorsal surface ; opposite face narrow, rounded ; extremity 

 abrupt, rounded and faintly sub-trilobate. Shell subquadrate. Beaks ter- 

 minal, and projecting beyond the buccal end of the shell, very much incurved, 

 so as to appear somewhat spiral. Umbones broad, slightly flattened in the 

 middle. Cardinal margin straight anteriorly, depressed posteriorly, merging 



[Oct, 



