182 MANUAL OF THE MOLLUSC A. 



spire small or concealed ; aperture long, rounded and sinuated in front ; lip 

 sharp. No operculum. 



Animal more or less investing tlie shell ; head a flattened disk,* with 

 tentacular lobes, often united ; eyes immersed in the centre of the disk, or 

 wanting ; foot oblong, fm-nished with a posterior lobe {meta-podium), and 

 side-lobes [eplpodia) ; gill single on the right side of the back, covered by 

 the shell; mantle-margin simple or expanded, and enveloping the shell. 

 Lingual dentition very various ; central teeth often wanting, laterals single 

 or numerous. Gizzard armed \sdth calcarious plates. Sexes united. 



The BidlidcE are animal-feeders ; they are said to use their lateral lobes 

 for swimming. About 150 recent species have been described by Mr. A, 

 Adams in Sowerby's Thesaurus Conchylionim. Fossil species date from 



the lower Oolites ; one is found in the Aralo-Caspian formation. 



•- 



Bulla, Lamarck. Bubble-shell. 



Type, B. ampulla, PL XIV. fig. 6. Syn. Haminea (hydatis) Leach. 



Shell oval, ventricose, convoluted, external or only partially invested by 

 the animal; apex perforated; aperture longer than the shell, rounded at 

 each end ; lip sharp. 



Animal with a large cephalic disk, truncated in front, bUobed behind, the 

 lobes laminated beneath; eyes sub-central, immersed or wanting; lateral 

 lobes very large, reflected on the sides of the shell, posterior lobe covering the 

 spire : foot quadrate ; gizzard furnished with 3 chiton-like plates ; teeth. ? 



Bulla naucum {Atys, Montf. AHcula, Ehr. Roxania, Leach). PI. XIV. 

 fig. 7 ; has the columella twisted, and the spire entirely concealed. 



Distr. 50 sp. In all temperate and tropical seas, especially on sandy 

 bottoms, ranging from low water to 25 or 30 fms. 



Fossil, 70 sp. Ool. — . S. America, U.S. Europe. 



Sub-genera ? Crypt-optlialmjis (smaragdinus) Ehr. Red sea. Shell 

 scarcely convolute, fragile, oval, convex, without spire or columella. Animal 

 semi-cylindi'ical, head with short tentacular lobes, eyes small, concealed under 

 the lateral margins of the head, mantle and lateral lobes enveloping the shell. 



PJianeropthalmtis, A. Adams. (Xanthonella, Gray) B. lutea, Quoy, New 

 Guinea. Shell oval, convex, pointed behind, columella margin with a curved 

 process. Anim.al long, cylindrical, head with short tentacular lobes, eyes in 

 middle of disk, lateral lobes enveloping. 



Linteria, A. Adams (Glauconella, Gray), Bulla viridis, Rang. PL XIV. 

 fig. 7. Shell oval, widely open, showing the rudimentary internal spire. 



* The cephalic expansion of the Bullidae is formed by the fusion of the dorsal and 

 oral tentacles. {Cuvier.) The tentacular lobes, or posterior part of the disk is sup- 

 plied with nerves from the olfactory ganglia; the anterior portion of the disk re- 

 ceives branches from the labial nerve, which comes from the front margin of the 

 cerebroid. (Hancock.) 



