Page:Natural History, Mollusca.djvu/206

From Wikisource
Jump to navigation Jump to search
This page has been validated.
194
PECTINIBRANCHIATA.—SCALARIADÆ.

Genus Scalaria.

The shell is spiral, consisting of many whorls, assuming a turreted form, ornamented with many elevated ribs, which cross the whorls in the same direction as the length of the shell; the aperture is rounded, with the lip thickened and entire. There is a horny operculum.

The animal has an angularly lunate head, with two long pointed tentacles, and eyes immersed at their bases; the mouth, which opens below, has a retractile proboscis; the mantle is rudimentary; the foot is triangular, grooved beneath, and furnished in front with a fold.

In the principal section of the genus, confined to the warmer parts of the globe, the whorls or turns of the spire do not touch each other in any direction: these are designated true Wentletraps. In this division is placed the shell above alluded to,