338 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.40. 



the summit, the third immediately posterior to the suture, while the 

 second is half way between these two. These cords are a little 

 wider than the spaces that separate them. In addition to the spiral 

 cords, the whorls are marked by somewhat retractive, axial ribs a 

 little less strong than the spiral cords. Of these 20 occur upon the 

 second, 22 upon the third and fourth, and 24 upon the penultimate 

 turn. The junctions of the axial ribs and spiral cords form well 

 rounded tubercles, while the spaces between them are small rounded 

 pits. Sutures well impressed. Periphery of the last whorl marked 

 by a deep spiral sulcus. Base moderately long with two tumid, 

 broad, rounded, spiral cords. Aperture irregularly oval, decidedly 

 channeled anteriorly; posterior angle obtuse; outer lip rendered 

 sinuous by the external sculpture; columella curved and twisted, 

 with the edge reflected; parietal wall covered with a thick callus. 



Tablet 2031, Liverpool collection, British Museum, contains Doctor 

 Carpenter's two cotypes which were collected on Spondylus at Mazat- 

 lan, Mexico. The largest of these cotypes measures : Length 1 .9 mm., 

 diameter 0.3 mm. Our figure is after a camera lucida drawing by 

 Doctor Carpenter of the type. 



CERITHIOPSIS (CERITHIOPSIS) ABREOJOSENSIS, new species. 

 Plate 37, fig. 4. 



Shell minute, elongate-conic, brown, excepting the nuclear whorls 

 which are white. Nuclear whorls four and one-half, well rounded, 

 smooth, separated by a moderately constricted suture, forming an 

 elevated, cylindric spire which gives the apex of the shell a mucronate 

 appearance. Post-nuclear whorls very slightly rounded, ornamented 

 by three spiral cords, the first of which is at the summit, the second 

 at the anterior termination of the posterior third between the sutures, 

 while the last is considerably posterior to the suture. The median 

 cord, therefore, is much nearer the cord at the summit than that at 

 the suture. In addition to these spiral cords, the whorls are marked 

 by very slightly retractive, axial ribs which are almost as strong as 

 the spiral cords. Of these ribs 16 occur upon all but the penultimate 

 turn, winch has 18. The junctions of the axial ribs and the spiral 

 cords form well rounded tubercles, while the spaces enclosed between 

 them are elongated slits between the first and second spiral cords 

 and elongated, almost squarish pits between the median and the 

 peripheral cord. Sutures strongly constricted. Periphery of the last 

 whorl marked by a spiral sulcus as wide as that winch separates the 

 supraperipheral cord from the median cord between the sutures, and 

 crossed by the continuations of the axial ribs. Base moderately 

 long, marked by two strong, spiral cords, one of which is immediately 

 below the periphery, while the other is a little posterior to the middle 

 of the base, the two being separated by a channel equaling the periph- 



