456 MANUAL OF THE MOLLUSCas. 
from the Philippines, a8 seen on remoying the left valve, and 
part oj' tne mantle within the pallial line; b-c. the large pedal 
opening; the arruws indicate 
ths small plaia incurrent orifice, 
and the valvular excurrent ori- 
fice; f, the foot, contracted in 
KY spirit; pp, the large striated 
\ 5 palpi; 7, the liver; the outer 
i)  giilhas a simple margin, the 
pijgy~ inner is grooyed and conducts 
to the mouth. This genus has 
higher claims than Kellia to be 
regarded as the type of a 
family. 
Luctna, Bruguiere. - 
= 
z 
J 
A f 
Fig 255. Diplodonia. 
Etymology, Lucina, a name of Juno. 
Type, us. Penosylvanica, Pl. XIX., Fig. 6. 
Shell orbicular, white; umbones depressed; lunule distinct; 
margins smooth or minutely crenulated; ligament oblique, 
semi-internal; hinge-teeth 2.2, laterals 1—1 and 2—2, or obso- 
lete; muscular impressions rugose, anterior elongated within 
the pallial line, posterior oblong ; umbonal area with an oblique 
furrow. 
Animal with the mantle freely open below; siphonal orifices 
simple; mouth minute, lips thin; gills single on each side, very 
large and thick; foot cylindrical, pointed, slightly heeled at the 
base. 
The foot of Zucina is often twice as long as the animal, but is 
usually folded back on itself and concealed between the gills; 
it is hollow throughout. JL. lactea (Loripes, Poli.) has a long 
contractile anal tube. ZL. tigrina (Codakia, Scop.) has the liga- 
ment concealed between the valves, its lateral teeth are obsolete. 
Distribution, 76 species. West Indies, Norway, Black Sea, 
New Zealand; 120 fathoms. 
Fossil, 250 species. U. Silurian —. United States — T. del 
Fuego; Europe — Southern India. 
Sub-genera, @ryptoden, Turton. lL. flexuosa, Pl. XIX, 
Fig. 7. Synonyms, Ptychina. Phil. Thyatira, Leach. Clausina 
(ferruginosa) Jeffr. Shell thin, edentulous; ligament quite in- 
ternal, oblique. Animal with a long anal tube. Distribution, 
5 species. Norway — New Zealand. Soss¢l, 2 species, Hocene —. 
United States, Europe. 
Psathura, Deshayes. Anterior adductor scar long, narrow; 
hinge-teeth 2.2; umbones imperceptible. 
