PLATE XX. 
a Edmondia sulcata, Phillips. Left aspect (natural size) of a cast. Carboniferous 
Limestone, Redesdale, Northumberland. 
2. — — The same specimen with the umbone removed (by the dark 
line on the latter figure), showing the left cartilage 
muscular fulcrum (@). 
3. — — The left cartilage. muscular fulcrum enlarged. 
4. — o Both cartilage muscular fulcra (enlarged), as seen on the 
specimen at fig. 2, when looking on its dorsal 
aspect. 
5. Allerisma sulcata, Meming. Left aspect (natural size) of a cast, showing impres- 
sions of the anterior and posterior adductor muscles 
(a, 6); sinus in the pallial line (©); and _ pimples 
radiating over the posterior half of the shell. Car- 
boniferous Shale, Redesdale, Northumberland. 
6. Lepteena analago, J. de C. Sowerby. Fotaminiferous valve, twice the natural size : 
testiferous. a, teeth; 6, saucer-shaped muscular ful- 
crum; ¢, ventral median plate; d, fissure; e, foramen ; 
J, (:) cardinal muscular impressions; g, (?) valvular 
muscular ditto; #, superior pedicle muscular ditto; 
2, primary trunks of vascular system; /, area. Car- 
boniferous Shale, Redesdale, Northumberland. 
(The letter d referring to the fissure—that is, the triangular 
opening between the teeth a—has been inadvertently omitted.) 
the — — Imperforate valve. a, dental sockets; 6, dorsal median 
® plate ; c, impressions of the anterior divisions of the 
valvular muscles; d, ditto of the posterior divisions ; 
e, cardinal muscular fulcrum (divided); 4, primary 
trunks of the vascular system passmg out from 
between the divisions of the adductor muscular im- 
pressions; g, area. Same locality as last. 
(The reference letter, 4, is cancelled.) 
8. Anomia ephippium, Zamveus. Upper valve, rather enlarged, to show the dendritic 
character of the impression of the stopper muscle (a). 
9. Criopus turbmatus, Pol. Attached valve (enlarged), showing the digitated genito- 
vascular impressions (in relief), a. 
