no. 1823. MOLLUSKS OF THE GENUS CERITHIOPSIS— BARTSCH. 337 



three spiral cords of which the first is a little below the summit, the 

 second median and the third a little posterior to the suture. These 

 cords are separated by spaces a little wider than the cords. In addi- 

 tion to the spiral sculpture, the whorls are marked by decidedly 

 retractive, axial ribs which are about as strong as the spiral cords. 

 Of these ribs, 12 occur upon the first and second, 14 upon the third, 

 IS upon the fourth, and 20 upon the penultimate whorl. The 

 junctions of the axial ribs and spiral cords form well rounded tuber- 

 cles, while the spaces enclosed between them are deep, rounded pits. 

 Sutures moderately constricted. Periphery of the last whorl marked 

 with a strong, smooth, spiral cord which is separated from the first 

 supraperipheral cord by a channel as wide as that which separates 

 the supraperipheral cord from the median and, like it, is crossed by 

 the continuations of the axial ribs, which extend to the posterior 

 edge of the peripheral cord. Base moderately long, well rounded, 

 marked by two broad rounded, spiral cords. Aperture irregularly 

 oval, decidedly channeled anteriorly; posterior angle obtuse; outer 

 lip rendered sinuous by the external sculpture; columella curved, 

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

 Nine specimens of this species were reported by Doctor Carpenter 

 taken from Spondylus and Chama at Mazatlan. The cotypes are on 

 Tablet 2028, Liverpool collection, British Museum. The larger, a 

 perfect specimen with seven post-nuclear whorls, measures: Length 

 3.75 mm., diameter 1.2 mm. Our figure is after a camera lucida 

 sketch of the type by Doctor Carpenter. 



CERITHIOPSIS (CERITHIOPSIS) TUBERCULOIDES, var. ALBONODOSA Carpenter. 



Plate 37, fig. 3. 

 Cerithiopsis ? tuberculoidcs albonodosa Carpenter, Cat. Maz. Shells, 1857, p. 443. 



Of this Doctor Carpenter says : 



Shell similar to tuberculoides with the tubercles more distant and white. Nuclear 

 whorls four, less elevated and subcarinate. 



Tablet 2029, Liverpool collection, British Museum, contains a 

 young shell and a fragment of an adult shell taken from Spondylus 

 at Mazatlan, Mexico. 



Our figure is after a camera lucida sketch of the type by Doctor 

 Carpenter. 



CERITHIOPSIS (CERITHIOPSIS) PUPIFORMIS Carpenter. 



Plate 38, figs. 1 and 5. 

 Cerithiopsis pupiformis Carpenter, Cat. Maz. Shells, 1857, pp. 443-444. 



Shell minute, elongate-conic, brown. Nuclear whorls four, smooth, 

 separated b} T a constricted suture forming a mucronate apex. Post- 

 nuclear whorls marked by three spiral cords of which the first is at 

 80796°— Proc.N.M.vol. 40—11 22 



