CLASS GASTROPODA 
245 
Seguenzia cervola Dali, 1919 
Proceedings of the United States National Museum, 56:344. 
Shell small, white, slightly depressed, with one small, smooth nuclear 
whorl and five subsequent whorls flattened a little in front of a distinct 
suture, separated by a somewhat convex, smooth fasciole from a thread¬ 
like keel above the periphery; in front of this is a wide, smooth interval; 
on the base are about a dozen spiral threads with wider interspaces, and 
very faint microscopic spiral striae are visible in all the interspaces under 
a lens; on the upper whorls there is a small thread between the keel and 
the suture, and near the apex they become obsolete; at the aperture is a 
shallow sulcus between the keel and the suture and a smaller one at the 
middle of the base; there is a sharp notch below the end of the thin, arcuate 
projecting pillar, behind which is a moderately large twisted umbilicus; 
the body shows no glaze; the base of the shell is conspicuously convex. 
Height, 4.5; diameter, 5 mm. (Dali.) 
Type in United States National Museum, No. 209229. Type locality, 
U.S. Fish Commission Station 4381, off North Coronado Island, in 618 to 
692 fathoms. 
Range. Known only from type locality. 
Seguenzia giovia Dali, 1919 
Plate 33, figs. 1, 2, 3 
Proceedings of the United States National Museum, 56:343. 
Shell resembling the preceding species, but larger and differently sculp¬ 
tured ; nucleus minute, smooth, subglobular followed by seven sculptured 
whorls; suture obscure, laid on the peripheral keel; spiral sculpture of 
four narrow prominent keels, of which the second is peripheral, the third 
marginates the base, and the fourth is on the base, the interspaces much 
wider and becoming narrower anteriorly; there are also seven closer even 
low threads on the base with subequal interspaces; the posterior wide 
interspaces are sculptured with close-set, fine, spiral threads; axial sculp¬ 
ture of numerous equal and equally spaced arcuate threads, with wide 
interspaces, which on the upper whorls bead the posterior carina, but later 
are chiefly visible in the interspaces and extend over the whole shell; the 
sulcus at the aperture next the body is shallow, the outer lip beyond it 
moderately produced and crenulate by the sculpture; the thin and arcuate 
pillar has a very small notch at its base; and there is a deep twisted per¬ 
forate umbilicus and a thin layer of enamel on the body. Height, 6; 
diameter, 5 mm. (Dali.) 
Type in United States National Museum, No. 209228. Type locality, 
U.S. Fish Commission Station 4408, off Catalina Island, California. 
Range. Known only from type locality. 
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