136 MANUAL OF THE MOLLUSC A. 



Animal with an elongated (non-retractile ?) proboscis ; tentacles long and 

 slender, with sessile eyes at their outer bases ; sides plain j foot narrow, 

 elongated behind. (Adams.) Related to scahtria ? 



Most of the phori attach foreign substances to the margins of their shells, 

 as they grow ; particular species affecting stones, whilst others prefer shells or 

 corals. They are called " mineralogists," and " conchologists," by collectors ; 

 P. Solaris and P. indicus are nearly or quite free from these disguises. They 

 are said to frequent rough bottoms, and to scramble over the ground, like the 

 strombs, rather than glide evenly. 



Distr., 9 sp. "W. Indies, India, Malacca, Philippines, China, \V. America. 



Fossil, 15 sp. Chalk ? Eocene. Brit., France. Shells extremely like 

 the recent phorus, are met with even in the carb. limestone. 



LACUNA, Turton. 



Etym., lacuna, a fissure. 



Type, L. pallidula, PI. IX., fig. 16. Syn., medoria, Gray. 



Shell, turbinated, thin ; aperture semi-lunar ; columella flattened, with 

 an umbilical fissure. Operc. pauci-spiral. 



Animal, operculigerous lobe furnished with lateral wings and tentacular 

 filaments. Teeth, 5 casped ; uncini 1, 2 dentated, 3 simple. Spawn (ootheca} 

 vermiform, thick, semicircular. Range, low- water 50 fathoms. 



Distr., Northern shores, Norway, Brit., Spain. Fossil, 1 sp. Glacial 

 beds, Scotland. 



? LITIOPA, Rang. 



Etym., litos, simple, ope, aperture. 



Type, L. bombix. PI. IX., fig. 24. 



Shell minute, pointed ; aperture slightly notched in front ; outer lip sim- 

 ple, thin ; inner lip reflected. Operc. spiral. 



Distr., Atlantic, Medit., on floating sea-weed, to which they adhere by 

 threads. Fossil, 1 sp. Miocene (Crag.). 



RISSOA, Fremenville. 



Etym., named after Risso,* a French zoologist. 



Type, R. labiosa, PI. IX., fig. 17. Syn., cingula, Mem. 



Shell minute, white or homy ; conical, pointed, many-whirled ; smooth, 

 ribbed, or cancellated ; aperture rounded ; peristome entire, continuous ; outer 

 lip slightly expanded and thickened. Operc. sub-spiral. 



The animal has long, slender tentacles, with eyes on small prominences 

 near their outer bases ; the foot is pointed behind ; the operculigerous lobe 

 has a wing-like process and a filament (cirrus) on each side. Lingual teeth 

 single, sub-quadrate, hooked, dentated ; uncini 3 ; 1 dentated, 2, 3, claw- 



* It is much to be regretted that some modern naturalists have tried to find out 

 and bring into use the obscure genera of Risso, and the worthless fabrications of Mont- 

 fort and Rafinesque, which had better have remained unknown. 



