394 THE OCEAN WOULD. 



bands, separated by many varied tints, cause these little molluscs to 

 be much sought after for ornamental collections. The shell itself is 

 oval or globulous, rolled up in a scroll, smooth, spotted, very thin and 

 fragile, with a concave spiral, umbilicate, open in all its length, with 

 a straight, wide, and cutting edge. 



Obtuse at its two extremities, neither the head of the animal nor 

 the tentacles are very apparent. The gills are placed under the back, 



Figs. 183 and 184. Bulla ampulla (Linnseus). 



a little to the right and behind ; its stomach, which alone*fills a great 

 part of the cavity of the body, presents the peculiarity, already noted 

 in the Aplysia, of being furnished with bony pieces, evidently intended 

 to grind the food. 



The Bullae can swim with facility in deep water, but they evidently 

 prefer the shallows and a sandy bottom, feeding upon smaller mol- 



Fig. 185. Bulla oblonga Fig. 186. Bulla aspersa Fig. 187. Bulla nebulosa 



(Adams). (Adams). (Gould). 



luscs. They are found in every sea, but they abound chiefly in the 

 Indian Ocean and Oceania. Some species, however, such as Bulla am- 

 pulla (Figs. 183 and 184), the shell of which is shaded grey and 

 brown, and the Water-drop (Bulla hydratis), inhabit European seas. 

 Bulla oblonga and Bulla aspersa (Adams), and Bulla nebulosa 



