LAMELLIBRANCHIATE CONCHIFERA. 101 
ANATOMICAL CLASSIFICATION OF THE LAMELLIBRANCHIATA. 
Lamellibranchiate Bivalve Animals. 
hind; tubes small, united.... CyTHEREA. 
foot securiform ; tubes larger 
and more or less distinct...... Venus—Astarte, &c. 
foot small; branchie of each 
united; | branchie 
mantle | footva- | disunited 
open | rious... | medianly. 
mantle only open infe- { tubes 
gx tentacles very longs not distinct from the branchiw, branchiz all united ; an additional museu- 
Ss 2 lar system.. .. ANom1A—Placuna. 
a .. OstREA—Gryphea. 
<3. 
Sag 
& 23 PRE IMANGC |, cevessescnvenssonesonvscdsussdoncee Pecren—Pedum. 
~e z foot short, thick, with a disk at the extre- 
a3 mity, from the centre of which eens a 
Se tentacles short, se- branchie disunited | pedicellated oval body; ocelli ............... SpeonpyLus—Plicatula. 
os parate from the medianly ......:... | foot compressed ; no ocelli 
a= branchiz ......... La foot.. branchie conjoined medianly .......... ceecb ea 
mantle without separate (foot slender, byssiferous ; tentacles fringed 
orifices or tubes......... | foot thick, rounded, with a callosity ........ oe 
. foot compressed, securiform.......... vveesencencnzere +++. PECTUNCULUS. 
foot oval below, its margin tentacular ; tentacles volute «. NucuLa. 
foot large, pointed anteriorly, bent at an angle .... «sees TRIGONIA*. 
foot small, bys- {anterior muscle small; ( byssus di dto its base. Myrixus. 
siferous ...... | retractile musclesofthe | byssus with a common 
foot numerous; byssus< corneous centre ......... MODIOLA. 
mantle with a distinct TAT ge .sccccessseecenens ... | anusfurnished with a long 
anal orifice......... sesens ligulate valve ......... eee PINNA*, 
muscles equal, two pairs of retractile muscles only ; 
byssus rudimentary eve . LirHopomus. 
| foot large, not byssiferous........ : .. Unto—Cardita, Hyria, &c. 
mantle widely open ..... sseeeeeeee CARDIUM—Cyprina. 
mantle with a superior foot ee and discal, byssiferous ; anterior muscle eee 
See ie a mantle closed foot small, cylindrical, bent at an angle; ‘lips fo- 
~ around the] liated ........ aa sssseess CHAMA*, 
foot or byssus | foot small, sharp ; lip: .. lsocanp1a*—Diceras. 
branchie not pro- { mantle closed around the foot......... 5 ssseeeeeeeeee LORIPES*—Lucina. 
duced into the tubes disunited; {foot large, rather falciform ; 
’ lower tube......... foot lanceolate... external branchie shortened ; 
mantle tentacular; labial ten- 
tacles large ....++.2++esseee+++e. DONAX—Capsa. 
3 foot small; external branchize 
4 shortened ; ; edge of mantle 
| simple; tentacles small ...... Psammosra—Soletellina, &c. 
§ — foot moderate; external bran- 
“5s chiz as long as the internal; 
<8 tentacles large; margin of the 
eo mantle entire ..........0s.s.08. TELLINA. 
rs 3 foot small; branchie equal; 
Se mantle tentacular.............. AMPHIDESMA. 
B= branchie { tubes small, partially divided ; 
<= united foot very long, obtuse......... Cyctas—Cyrena, &c. 
5 medianly. | tubes small, united to the ex- 
tremity; foot very long and 
pointed .. ........... seeseseeeeee MACTRA. 
tubes tubes large, foot short and 
more prominent behind ......... +». VENERUPIS. 
or less {es lanceolate, prominent be- 
riorly for the protru- | small; side united into one ......... . Panpora—Osteodesma. 
sion of the foot ...... | lipslong.) foot larger; branchiw sepa- 
THC anchesraeceweperarices «ssee4ee CORBULA—Sphenia, Thracia, &e. 
foot not byssiferous; tubes 
tubes large and coriaceous . .«. Mya—Anatina, Lutricola, &c. 
long; lips ) foot byssiferous ; tubes mode 
small..... | rate sseceeeseeeee HIATELLA—Byssomya, &c. 
foot long, club-shaped; tubes short .... «+++. SOLEN—Sanguinolaria, &c. 
two distinct adductor muscles; anterior 
one situated below a reflected portion of 
branchie pro- the mantle, uniting the beaks instead of 
mantle duced into, or a cartilage; tentacles large.........-...+e... PHOLAS—Gastrochena, &c. 
with two | attached to the body very elongated; adductor muscles 
produced | lower tube ; mantle foot very | united; end of mantle with two calcare- 
tubes, or | tubes always | open an-| short, ous pieces; tentacles small; no cartilage 
siphons .. Lunited ......... teriorly .. | rounded. |_ nor reflected portion of mantle ............ TEREDO. 
* For the anatomy of those marked with an Asterisk the author is indebted to Cuvier, Poli, or Blainyille. 
