CLASS GASTROPODA 
27 
equal areas. The cord at the summit is very slightly below the summit and 
renders this strongly shouldered. In addition to the spiral sculpture, the 
whorls are marked by almost vertical axial ribs which nearly equal the 
spiral cords in strength. Of these, 14 occur upon the first, 16 upon the 
second, 18 upon the third, 20 upon the fourth, 22 upon the fifth, and 25 
upon the penultimate turn. The intersections of the spiral cords and the 
axial ribs form well-rounded tubercles, while the spaces inclosed between 
them are well-impressed, squarish pits on all but the last; on this they are 
oblong, their long axes coinciding with the axial sculpture. Sutures 
strongly constricted, showing the peripheral cord on the later whorls. 
Periphery of the last whorl marked by a slender, smooth cord, the space 
between which and the first supraperipheral cord is about as wide as that 
which separates the next two cords posteriorly and is crossed by the 
continuations of the axial ribs which terminate at its posterior border. 
Base marked by five subequally spaced spiral cords, of which the strongest 
is immediately below the periphery and is equal to the peripheral cord, 
while the next two in strength are at the columella; the two intervening 
are slender threads. Entire surface of spire and base crossed by numerous, 
rather strong lines of growth. Aperture broadly oval, decidedly channeled 
anteriorly; posterior angle obtuse; outer lip rendered sinuous by the ex¬ 
ternal sculpture; columella short, somewhat twisted, curved and reflected; 
parietal wall covered with a thick callus. Length, 7.3; diameter, 2.5 mm. 
(Bartsch.) 
Doctor Carpenter’s cotypes in United States National Museum, No. 
14823. Type locality, Monterey and Santa Barbara, California. 
Range. Monterey to San Diego, California. 
Described as Ccrithiopsis purpurea. 
Bittium challisae Bartsch, 1917 
Plate 74, figs. 2, 6 
Proceedings of the United States National Museum, 52:673; PI. 47, figs. 2, 6. 
Shell very large, white. Nucleus and early post-nuclear turns decollated, 
those remaining slightly shouldered at the summit, weakly rounded in the 
middle and decidedly contracted immediately above the suture, marked by 
rather strong, low, well-rounded, axial ribs of which 14 occur upon the 
second and third, 16 upon the fourth to sixth, 18 upon the seventh, and 20 
upon the last turn. The spiral sculpture consists of four cords on the early 
whorls, of which the first, at the summit, is a little weaker than the rest. 
These primary cords are truncated posteriorly and slope gently anteriorly. 
Beginning with the fourth whorl an intercalated thread makes its appear¬ 
ance between all the cords and between the summit and the first cord. 
[ 629 ] 
