348 SHELLS AND SHELL-FISH. PART II. 



Shell turbinate, mostly trochiform *, the substance almost 

 always perlaceous ; outer lip never thickened ; aperture 

 entire, closed by a shelly or horny operculum. 



SUB-FAM. SENECTIN^:. Snake Shells. 



Operculum round ; calcareous ; shell turbinate ; the 

 basal whorl ventricose ; pillar always smooth ; aperture 

 round, rarely oblique. 



SENECTUS Humph. Imperforate; the base 

 produced into a broad flat lobe ; spire 

 rather elevated and pointed ; the 

 whorls convex ; aperture perfectly 

 round ; not more oblique than Helix ; 

 inner lip entirely wanting, (jig. 110.) 



imperialis. Mart. 180. f.1790. radiatus. Mart. f. 1788-9. 



marmoratus. E. M. 448. f. 1. margarltaceus. Ib. f. 1762. 



pethiolatus. Mart. f. 1777-8. Sprenglerianus. Ib.f. 1801-2. 



cornutus. Ib. 179. f. 1779-80. crenulatus. Ib. f. 1811-12. 



setosus. En. Meth. 448. f. 4. hippocastanum. Ib.f. 1807-10 



argyrostomus. Mart. f. 1766. coronatus. En. M. 448. f. 2. 



chrysostomus. Ib. f. 1766. angulatus Sw. Sow. Gen. f. 8. 



MABMABOSTOMA Sw. Umbilicus deep ; spire of few 

 whorls, much depressed, and obtuse ; inner lip ob- 

 solete ; base even more produced than in Senectus, 

 but never distinctly channeled. 



M. versicolor. Mart. 176. undulata. Chem. 169. f. 

 f. 1740, 1741. 1640, 1641. 



DELPHINULA Lam. Turbinate ; spire depressed, the tip 

 obtuse ; pillar almost entirely wanting ; the umbili- 

 cus being large and pervious; exterior of the shell 

 rough with tubercles or lamellar plates, (fig. 109 h.) 

 torquata. Mart. Conch. 2.f. 71. laciniata. En. Meth. 451. 

 lamellosa. Zool. J. v. p. 33 1 . f. 1 . 



CycLOCANTHAt Sw. Sub-depressed, trochiform; im- 



* Except Phasianella. 



t Resembles Tubicanthus, but the aperture is hardly perlaceous, the 

 body-whorl not flattened beneath, or the mouth oblique. 



