PLATE IV K—Continued. 
Linqula lamellata, Hall. 
Fig. 10. View from the pedicle-valve of an internal cast, retaining the impression of the lateral and central 
muscular scars and of the pallial sinuses. The matrix is filled with minute ovoid bodies (ova), 
which appear to be distributed wherever the sinuses and iheir branches have extended. About 
the anterior and lateral margins of the valve the matrix is the opaque mud of the sediment; 
elsewhere the spaces between the ova, fire translucent. X 3. 
Fig. 11. The opposite side of the same specimen ; also showing the muscular, vascular and septal impres¬ 
sions. The intermixture of the opaque matrix on this side is somewhat greater than on the 
other, obliterating the ova to some extent. X 3. 
Fig. 12. A thin section of a portion of this specimen, which shows the ovoid bodies to be opaque and 
homogenous. X 12 
Fig. 13. An enlargement of the surface of the cast; showing the appearance of the ova when magnified 12 
diameters. The vertical ridges are casts of radiating furrows on the interior of the valve. 
Niagara group. Near Hamilton, Ontario. 
LINGULOPS, Hall. 
Page 18. 
Lingulops Granti, sp. nov. 
Fig. 14. The interior of a brachial valve. X 6. 
Fig. 15. The interior of a pedicle-valve. The muscular area is here developed into a well-defined plat¬ 
form, while in the other species of the genus, L. Whitfieldi and L. Norwoodi, it still retains its 
linguloid character. X 6. 
Niagara group. Hamilton, Ontario. 
CONOTRETA, Walcott. 
, Page 104. v 
CONOTRETA RuSTl, Walcott. 
Fig. Hi. Anterior view of a pedicle-valve. The apical and anterior regions retain a portion of the shell, 
but elsewhere the shell is.removed, showing the impressions of the internal radiating muscular 
ridges. X 4. 
Fig. 17. An internal cast of a smaller pedicle-valve ; showing the impression of the strong.apical callosity, 
and the radiating ridges. X 8. 
Fig. 18. An apical view of the same valve ;* Showing the subtriangular posterior slope, and its 1 obscurely 
defined median furrow. ' X'S. 
Fig. 19. Cardinal view of a very young individual, in which the posterior slope is very faint. X 12. 
Trenton limestone. Trenton Falls, N. Y. 
Fig. 20. Cardinal view of another very small example, retaining the shell. 
Fig. 21. Profile of same. X 25 
Hudson River group. Covington, Ky. 
OBOLUS, Eichwald. 
Page 80. 
Obolus [?] pulcher, Matthew. 
Fig. 22. The exterior of a valve, retaining the shell and showing the character of its ornamentation. X 3. 
,St. John group. , Caton’s Island, Neiv Brunswick. 
D1SCJNA, Lamarck. 
Page 1 120. 
Discina striata, Schumacher. 
Fig. 23. The interior of a pedicle-valve. 
Fig 24. The exterior of a similar valve. Much enlarged. 1 
Recent. Cape Palmas. 
(After Davidson. Trans. Linnean Soc., Ser. 2, Zool., vol. iv, pi. 25, figs. 24, 25. 1889.) 
