62 MOLLUSCA. GASTEROPODA. 



and has four tentacula, of which two are placed near the mouth, and the other two 

 more behind. The branchial scutellum is corneous or cretaceous.* 



Gen. 6. DOLABELLA, Lam. 



Body oblong, narrowed before, widened posteriorly, with the 

 borders of the mantle folded over the back ; four semitubu- 

 lar tentaculi disposed in pairs ; branchial operculum inclosing 

 a shell ; anus dorsal, near the branchiae ; shell oblong, slight- 

 ly arched, thick, callous, and somewhat spiral on each side. 



D. Rumphii, Cuv. Shell with the base thick, callous, subspiral, 

 dilated, wedge-shaped, and thin above. Inhabits Indian Ocean. 

 An. Mus. v- pi. 29, fig 1, 4. 



Gen. 7. LAPLYSIA, Lin. 



Body oblong, convex, bordered on each side by a large mantle, 

 which in repose covers the back ; head with a neck and four 

 tentacula, of which the two are upper and auriform, and the 

 other two near the mouth ; eyes sessile ; scutellum semicir- 

 cular, subcartilaginous, fixed on one side, and covering the 

 branchial cavity ; anus behind the branchiae. 



L. depilans, Lin. Body livid, blackish brown ; obtuse behind. In- 

 habits European seas. B. Penn. Brit. Zool. iv. pi. 23, fig. 1. 

 When this animal is touched, a whitish fetid mucous matter exudes from the body, 



which excites nausea and vomiting. It is said also that it occasions the hair to fall 



off; hence the specific name. 



FAMILY III. BULLACEA. 



Branchiae placed in a particular cavity towards the posterior 

 part of the back, and covered by the mantle ; no tentacula. 



All the species of this family are destitute of tentacula and branchial operculum 5 

 and have the head scarcely distinct. In some the animal has no shell either interior or 

 exterior ; in others it is completely concealed in the mantle ; and in others again 

 there is an external shell attached by a muscle. The shell in this family is so widened 

 that there is no apparent columella. Fossil species are found in Britain in the Lon- 

 don clay. 



Gen. 8. BULLA, Lam. Lin. 



Body oval-oblong, slightly convex, divided above into two 

 transverse portions, with the mantle folded posteriorly ; bran- 

 chiae covered ; anus on the right side ; body behind covered 

 by an external oval involute shell, destitute of pillar and 

 spire, and open in its whole length. 



B. lignaria, Lin. Shell oblong, narrowed towards the spire, trans- 

 versely striated, pale yellowish brown, with numerous transverse 

 striae of a lighter colour ; spire truncated, umbilicated. 2 inches 

 long. Inhabits European seas. B. Penn. Brit. Zool. iv. pi. 73. 



B. ampulla, Lin. Shell oval or subglobose, tumid, white or cine- 

 reous, dotted in waves, and marked with various shades and spots 

 of reddish brown and blue ; vertex umbilicated. 2 inches long. 

 Inhabits European and American seas. B. Mont. Test.pl. 7- fig- L 



3 



