No.1139. DEEr-WATEIl MOLLUSCAVERBILL AND HUXH. 845 



middle, where it is narrowest, it is nearly smooth and rounded, with 

 only slight indications of one or two transverse teeth on each side; 

 next these there are two or three somewhat oblique, slightly divergent, 

 irregular, longitudinal, slightly striated and crenulated folds, separated 

 distally by rather deep grooves nearly parallel with the inner margin. 

 The inner edge of the ventral margin is thin and plain. 



Length, 8.5 mm.; height, 7 mm.; thickness, <> mm. 



One living specimen (No. 74081) was dredged by the 7>V/r//<> at station 

 52, oft' Cashes Ledge, in 27 fathoms, 1S74. 



As only a single specimen has been found, it is possible that it is but 

 an abnormal variety, although it appears to have been healthy and 

 well-grown in every respect. It is related to I> pectunculoides (Plate 

 LXX VII, tig. (i), but differs remarkably in the character of the hinge, 

 which has the transverse teeth scarcely discernible, and oblique, irreg- 

 ular folds on the distal parts of the margin, and also in the greater 

 width of the ligamental area. 



Family LIMOPSIIXK. 



LIMOPSIS SULCATA, new species. 



(Plates XCII, fig. 2; XCV, tig. 9; XCVI, lig. 1.) 



Shell very oblique (young specimens are less oblique and in some 

 cases are more nearly circular), broad ovate, the posterior ventral mar- 

 gin much produced and obtusely rounded; auricles only slightly devel- 

 oped. The dorsal margin is short and straight, with a narrow, smooth 

 area beneath the beaks; the anterior margin is subtruncate, or very 

 obtusely rounded; the ventral margin is oblique, broadly rounded, 

 forming an obtusely rounded angle with the posterior margin, which is 

 strongly sloping and only a little convex. The umbos are small and 

 somewhat prominent; the beaks small, pointed, and curved inward. 

 The entire surface is covered with strongly marked, concentric grooves 

 and prominent rounded, narrow ribs; the latter are crossed by numer- 

 ous fine, radiating, incised striatious, which divide them into beadlike, 

 or squarish, portions, which are most obvious on the middle and pos- 

 terior parts and become very faint anteriorly. The hinge-margin is 

 much thickened and bears a curved series of rather large, flattened 

 teeth, of which about eight are situated in front of the beaks and about 

 ten behind them; those nearest the center are small; the resilial pit 

 extends upward to the beak in the form of a small triangular depression. 

 The inner surface of the shell is marked by fine, radiating stria-; the 

 margin is thickened and cut away near the edge; no crenulations have 

 been observed in our specimens. 



Greatest length, 12 mm.; greatest height, 13 mm.: breadth, 6 mm. 



A number of separate valves, at about ten stations, between X. hit. 

 40 8', W. long. 68 45', and K lat. 37 1' 4", W. long. 74 35' 40", in 

 64 to 349 fathoms, 1880-1884. 



