816 MANUAL OF THE MOLLTJSCA. 



The Bullidce are animal feeders ; they are said to use their 

 lateral lobes for s-wimming. About 150 recent species have 

 been described by Mr. A. Adams in Sowerby's Thesaurus Con- 

 chyliorum. Fossil species date from the lower Oolites ; one ifl 

 found in the Aralo-Caspian formation. 



Bulla, Lamarck. Bubble-shell. 



Type, B. ampulla, PI. XIV., Fig. 6. 



Synonym, 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, bilobed 

 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. Alicula, Ehr. Roxania, Leach). 

 PI. XIY., Pig. 7 ; has the columella twisted, and the spire 

 entirely concealed. 



Distribution, 50 species. In all temperate and tropical seas, 

 especially on sandy bottoms, ranging from low water to 25 or 30 

 fathoms. 



Fossil, 70 species. Oolite — . South America, United States, 

 Europe. 



Sub-genera ? Crypt-opthalmus (smaragdinus), Ehr. Red Sea. 

 Shell scarcely convolute, fragile, oval, convex, without spire or 

 columella. Animal semi- cylindrical, head with short tentacular 

 lobes, eyes small, concealed under the lateral margins of the 

 head, mantle and lateral lobes enveloping the shell. 



Phaneropthalmus, A. Adams. (Xanthonella, Gray) B. lutea, 

 Quoy, New Guinea. Shell oval, convex, pointed behind, 

 columella margin with a curved process. Animal long, cylin- 

 drical, head with short tentacular lobes, eyes in middle of disk, 

 lateral lobes enveloping. 



Linteria, A. Adams (Glauconella, Gray ; Smaragdinella, A. 

 Adams), Bulla viridis, Rang. PL XIY., Fig. 8. Shell oysI, 

 widely open, showing the rudimentary internal spire. Animal 

 with a squarish, disk-like head, eyes sessile in the centre ; 

 mantle not investing ; a posterior lobe ; lateral lobes envelop- 

 ing. 



ACERA, Miillcr. 



Type, A. bullata, PI. XIV., Fig. 9. 

 Etymology, Akeros, hornless. 



