PLATE IV g. 
Legend. B. Brachial valve. 
P. Pedicle-valve. 
F. Foramen. 
p. Pedicle-callosity (in brachial valve), 
g. Pedicle-groove. 
g / . Base of groove. 
1. Walls of groove, 
s. Median septum, 
o. Posterior muscular scars. 
c. Central scars, 
pc. Posterior centrals, 
cc. Median centrals, 
ac. Anterior centrals, 
pa. Posterior adductors. 
pa / . Anterior element of posterior ad¬ 
ductors. 
aa. Anterior adductors. 
TREMATIS, Sharpe. 
Page 138. 
Trematis terminalis, Emmons. 
Fig. 1. The interior of a brachial valve; showing the posterior and central muscular scars and the lingui- 
form median elevation. X 3. 
Fig. 2. An internal cast of the pedicle-valve ; showing the great depression of the pedicle-area, the 
median ridge corresponding to the pedicle-groove, and the vascular sinuses. X 3. 
Trenton limestone. Middleville, N. Y. 
Trematis, sp., compare T. punctostriata, Hall. 
Fig. 3. The internal pedicle-area; showing the elevation of the margins of the fissure. X 4. 
Hudson River group. Frankfort, Ky. 
Trematis millipunctata, Hall. 
Fig. 4. The interior of a brachial valve ; showing the posterior callosity forming a surface for the passage 
of the pedicle, the external muscular scars and the components of the central impressions. X 2. 
Hudson River group. Covington, Ky. 
Fig. 5. An internal cast of a brachial valve, to which a portion of the shell adheres. X 2. 
Fig. 6. The exterior of a brachial valve, from which the shell is partially exfoliated. X 2. 
Fig. 7. Profile of an internal cast of the conjoined valves. 
Fig. 8. Anterior view of the same specimen, exposing the pedicle-valve and the projecting apical p 
of the brachial valve. X 2. 
Hudson River group. Cincinnati, Ohio. 
Fig. 9. The interior of a brachial valve; showing the posterior''muscular scars beneath the broken pedi¬ 
cle-callosity. X 1.5. 
Hudson River group. Frankfort, Ky. 
Fig. 10. The external ornamentation. X 25. 
Trematis punctostriata, Hall. 
Fig. 11 j The exterior of a brachial valve. X 2. 
Fig. 12. The interior of a pedicle-valve. X 2. 
Fig. 13. The external ornamentation. X 25. 
Trenton limestone. Clifton, Tenn. 
Trematis fragilis, Ulrich. 
Fig. 14. A pedicle-valve ; showing the short and narrow pedicle-fissure. 
Hudson River group. Bank Lick Creek, Ky. 
Trematis Ottawensis, Billings. 
Fig. 15. External view of a brachial valve. From a gutta-percha cast of the exterior. Natural size. 
Fig. 16. The surface ornamentation. X 25. 
Trenton horizon. Frankfort, Ky. 
Fig. 17. The external pedicle-area, from a specimen referred with doubt to this species. X 3. 
Hudson River group. Cincinnati, Ohio. 
Trematis umbonata,, Ulrich. 
Fig. 18. The exterior of the brachial valve. X 2. 
Fig. 19. The same specimen, with the upper portion of the brachial valve removed, exposing the flat lower 
valve and its pedicle-fissure. X 2. 
From the original specimen figured by UmiCH (American Geologist, vol iii, No. 6, p. 378, fig. 8. 
1889). Hudson River group. Covington, Ky. 
