490 PHILOSOPHY OF ZOOLOGY. 



rather behind the tentacula. Penis exserted on the right 

 side of the neck, immediately behind the eye. Cloak large 

 in proportion to the size of the foot. We have termed the 

 genus Velut'ma, bestowing on the species the trivial name 

 vulgaris. 



B. Anterior margin of the aperture of the shell canali- 

 culated. 



This groove in the aperture of the shell is produced by 

 the anterior margin of the cloak being extended over the 

 opening into the gills, for the purpose of acting like a tube 

 or syphon, in conveying the water to and from the bran- 

 chial cavity. The species are considered as oviparous, with 

 distinct sexes in separate individuals. 



1. Shell convoluted. — The shell has an oval or linear mouth 

 parallel with its length. The whorls, which are small seg- 

 ments of large circles, are wrapped round the pillar, and 

 the one rising a little above the other, embrace or inclose 

 the preceding ones. The four following families appear to 

 belong to this division. 



Family 1. Commdfe. Furnished with a long proboscis, 

 and produced tentacula, with the eyes near the summit on 

 the outside. The lid is placed obliquely on the foot, and 

 is too small to fill the mouth of the shell. The genera 

 Conus and Terebellum form this family. 



Family 2. Cypreadce. Cloak enlarged, and capable of 

 folding over the shell. There is no lid. The genus Cyprea 

 is the type. 



Family 3. Ovuladee. Both extremities of the aperture 

 canaliculated. The inhabitants of all the genera, Ovula, 

 Calpurna, and Volva, are unknown. The last genus in- 

 cludes the Bulla patula of Penkant. 



Family 4. Volntada. Canal of the aperture abbreviated. 

 Pillar-lip plaited. The foot appears to be destitute of a lid. 

 The genera are numerous ; Voluta, Oliva, Cymbium, Mar- 



