180 MOLLUSCA. 



naeus, the spongy body is capable of changing its dimen- 

 sions, and enabling the animal to sink or rise in the water 

 at pleasure. When irritated, the animal ejects a purple fluid 

 from the cellular margin of the cloak above the gills, not 

 unlike the Aplysia. This species was added to the British 

 Fauna by the late Miss Hutchins. 



GENUS VELUTINA. Foot simple. This genus was form- 

 ed by us for the reception of the Sulla velutina of M tiller, 

 (Zool. Dan. tab. ci. f. 1, 2, 3, 4), the Helix Icevigata of Bri- 

 tish writers. The foot is destitute of lid or appendage, and 

 is broad before, and pointed behind. The tentacula are two 

 in number, short and filiform, with eyes at their external 

 base. The head is broad and short. In addition to these 

 characters given by Miiller,.we have been enabled to add 

 the following, from a specimen, somewhat altered, which was 

 found in the stomach of a cod-fish. The animal adheres to 

 the shell by two linear muscles, one on each side the cloak. 

 The branchial cavity is towards the left side. The tongue 

 is spinous, narrow, with its free extremity spiral. Eyes 

 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 Velutina, bestowing on the species the trivial name 

 vulgaris. 



In the following groups the anterior margin of the aper- 

 ture of the shell is canaliculated. This groove in the aper- 

 ture 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 branchial cavity. The species are 

 considered as oviparous, with distinct sexes in separate in- 

 dividuals. 



