104 GENUS XXII. BULLA. 



gizzard or stomach, which is well described in Linn. Trans. 



vol. 2. t. 3. f, 18. 



Linnaeus describes 23 species, Gmelin has added 27, and 



Dr. Turton 2. Total, 52. 



Lamarck divides this genus into seven, as follow, the first 



of which he places with the Naked Mollusca. 



BulljEA. Body creeping, oval-oblong, and convex, bordered 

 with membranes, which envelop it ; the head naked, 

 without tentacula or horns ; the hinder part of the body 

 furnished with a broad shield, including and covering the 

 gills, and containing the shell-like body (Bulla aperto 

 Linn. See/. 62). 



OvuLA. Shell tumid, more or less elongated to a point; at 

 the two ends the edges rolled inwards ; the aperture lon- 

 gitudinal, with no teeth on the left side (see Bulla Ovum, 

 Gualter. Test. t. 15. f. A.B.). 



Terebellum. Shell nearly cylindrical, spire-pointed ; the 

 aperture longitudinal and narrow at the upper part, with 

 a hollow at the base, and the pillar truncated (see Bulla 

 Terebellum, f. 63). 



Pyrula. Shell nearly pear-shaped, channelled at the base ; 

 the upper part swelling, with a short spire, without any 

 suture or ridge on the outside ; the pillar smooth, without 

 any notch or hollow on the right lip (see Bulla Ficus, 

 /. 64). 



Bulla. Shell swelled or gibbous ; the spire within concealed ; 



