324 MANUAL OF THE MOLLUSCA. 
lines of growth; apex sub-central, oblique, scarcely raised ; 
margins acute; inner surface with a central coloured and 
striated disk, surrounded by a continuous irregular muscular 
impression. It has a minute sinistral nucleus. 
Animal with a very large tuberculated foot, deeply notched 
in front; mouth small, proboscidiform, retractile into the pedal 
notch, covered by a small-lobed veil; dorsal tentacles ear- 
shaped, with large plicated cavities at their bases ; eyes small, 
sessile between the tentacles; mantle not extending beyond the 
shell; gill forming a series of plumes beneath the shell in front 
and on the right side; reproductive organ in front of the dorsal 
tentacles; excretory orifice posterior, tubular. 
Distribution, 6 species. Canaries, Mediterranean, India, China, 
Sandwich Islands. 
Fossil, 4 species. Oolite—. United States, Sicily, Asia. 
TyLopiInaA, Rafinesque. 
Type, T. punctulata, Raf. (— citrina, Joannis). 3 species. 
Mediterranean, Norway. 
Fossil, 1 species. Tertiary. 
Shell limpet-like, depressed, apex sub-central, with a minute 
spiral nucleus. 
Animal oblong, foot truncated in front, rather poimted 
behind; dorsal tentacles ear-like, with eyes sessile at their 
inner bases; oral tentacles broad; branchial plume projecting 
posteriorly on the right side. 
FAMILY V.—PHYLLIDIADZA. 
Animal shell-less, covered by a mantle, branchial laminz 
arranged in series on both sides of the body, between the foot 
and mantle. Sexes united. 
PHYLLIDIA, Cuvier. 
Type, P. pustulosa, Cuvier. 
Etymology, diminutive of phylion, a leaf. 
Animal oblong, covered with a coriaceous tuberculated 
mantle; dorsal tentacles clavate, retractile into cayities near 
the front of the mantle; mouth with two tentacles; foot 
broadly oval; gills forming a series of lamine extending the 
entire length of both sides; excretory orifice in the middle 
line, near the posterior end of the back, or between the mantle 
and foot; reproductive organs on the right side; stomach 
simple, membranous. 
Distribution, 5 species. Mediterranean, Red Sea, India. 
