o. 1139. DEEr-WATEK MOLLUSCA VERHILL A.\l> IlfSH. 787 



nearly straight, sloping- rapidly from the beak; the anterior end is dis- 

 tinctly produced, evenly rounded; the ventral margin is slightly but 

 regularly convex to the lower posterior fold; the posterior end is 

 marked by two distinct plications separated by a rather prominent 

 ridge which, at the margin, appears as a rounded projection separating 

 two reentrant curves; the postero-dorsal margin is convex, sloping 

 rapidly to the upper plication. The ligameiital area is relatively large, 

 long, elliptical, defined by a distinct groove. Internally the hinge- 

 margin is considerably thickened, especially directly under the beak, 

 where there is a slight swelling; the posterior ligament occupies a^ 

 very distinct groove, and extends forward under the tip of the beak. 



Length, 3..~> mm.; height, 3.75 mm. 



The shell here referred to this species appears to agree well with the 

 figures and descriptions given by G. O. Sars. It pretty closely resem- 

 bles some varieties of C. gouldii. The principal differences exter- 

 nally are in the somewhat more produced anterior end and the longer 

 and straighter antero-dorsal margin; the posterior plications are also 

 Jess strongly developed. 



Found in small numbers at about thirty stations north of Cape Cod, 

 between N. lat. 43 4-U', \V. long. 09 22', and K". lat. JL )0 30', W. long. 

 70o 3S' ? in 13 to 73 fathoms, 1873-1879. 



CRYPTODON CROULINENSIS (Jeffreys) Smith, variety ALTUS, new. 



(Pint.- LXXXVIII, figs. 1, 2.) 



Shell higher than long, larger than the common form. TJmbos promi- 

 nent, elevated and turned forward, so as to leave a rather large, con- 

 spicuous, flattened, lunular area, which is bordered externally by a 

 slight ridge, followed by a concave depression in the surface, which 

 forms a slight indentation in the anterior margin, and resembles the 

 posterior plication, but is more shallow. The antero-dorsal margin in 

 the lunular region is slightly concave, but slopes very rapidly; the 

 anterior end is a little more produced than the posterior, but both are 

 decidedly short; the ventral margin is pretty evenly rounded; poste- 

 riorly there are two distinct plications; the lower or larger one is mod- 

 erately sunken and extends from the beak to the posterior margin, 

 the upper one is much shorter and narrower and defines the narrow, 

 lanceolate, ligamental area; each produces a decided indentation in 

 the margin, that caused by the lower one being more sharply defined 

 and shorter than the other, these are separated by a well-defined, 

 curved, radiating ridge which extends a little below the margin; the 

 postero-dorsal margin is strongly convex, evenly rounded, with a rapid 

 slope; the hinge margin is considerably thickened, especially beneath 

 the beak, and in the right valve forms a distinctly raised tubercle. 



Length, 5 mm.; height, G mm. Eastport, Maine, 1870. 



Another specimen, from station 29L>, is slightly smaller. Length, 



