

PLATE 



IV G. 





B. 



Brachial valve. 





c. 



P. 



Pedicie-valve. 





pc. 



F. 



Foramen. 





cc. 



P- 



Pedicle-callosity (in brachial valve). 





ac. 



S- 



Pedicle-groove. 





pa. 



1. 



Base of groove. 

 Walls of groove. 





pa'. 



s. 



Median septum. 





aa. 



0. 



Posterior muscular scars. 







Legend, B. Brachial valve. c. Central scars. 



~ ~ "' ' " Posterior centrals. 



Median centrals. 

 Anterior centrals. 

 Posterior adductors. 

 Anterior element of posterior ad- 



ductoi's. 

 Antei'ior adductors. 



TREMATIS, Shakpe. 



Page 138. 



Tkematis terminalis, Emmons. 



Fig. 1. The intei'ior of a brachial valve; showing the postei-ior and central muscular scars and the lingui- 



form median elevation. X 3. 

 Fig. 2. An internal cast of the jiedicle-valve ; showing the great depi-ession of the pedicle-area, the 



median ridge corresponding to the pedicle-groove, and the vascular sinuses. X 3. 

 Ti-enton limestone. Middletnlle, N. Y. 



Teematis, sp., compute T. punctostriata, Hull. 



Fig. 3. The internal pedicle-area; showing the elevation of the margins of the fissure. X 4. 

 Hudson River group. Fi-ankfort, Ky. 



Trematis MILLIPUNCTATA, Hull. 

 Fig. 4. The interior of a bi'achial valve ; showing the posterior callosity foi'uiing a surface for the passage 

 of the pedicle, the external muscular scars and the components of the central impressions. X 2. 

 Hudson River gi-oup. Covington, Ky. 

 Fig. 5. An internal cast of a brachial valve, to which a poi'tion of the shell adheres. X 2. 

 Fig. 6. The exterior of a bi-achial valve, from which the shell is partially exfoliated. X 2. 

 Fig. 7. Profile of an internal cast of the conjoined valves. 



Fig. S. Anterior view of the same specimen, exposing the pedicle-valve and the projecting apical portion 

 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. 



Tkematis punctostriata, Hall. 



Fig. 11. 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, Uliicli. 



Fig. 14. A pedicle-valve ; showing the short and narrow pedicle-fissui-e. 

 Hudson River gi'oup. 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 sui'face ornamentation. X 25. 



Trenton hoi-izon. Frankfo-rt, Ky. 

 Fig. 17. The external pedicle-area, from a specimen referred with donbt to this species. X 3. 



Hudson River group. Cincinnati, Ohio. 



Trematis umbonata, Ulfich. 



Fig. 18. The exterior of the brachial valve. X 2. 



Fig. 19. The same specimen, with the upper portion of the brachial valve i-emoved, exposing the flat lower 



valve and its pedicle-fissure. X 2. 

 From the original specimen figui'ed by Ulkich (American Geologist, vol iii, No. 6, p. 378, fig. 8. 



1889). Hudson River group. Covington, Ky. 



