PLATE Vc. 



(Figures 1 , -2, 6-lS, '25-41, by R. P. Whitfielu; i, 5, III, 12-47, by E. Emmons; 3, 20-24, by J, C. McConnell.i 



Legend. A- Deltidiura. a. Anterior adductor scars, 



t. Teeth. a'. Posteiior adductoi' scars. 



b. Sockets. r. Diductor scars, 

 fp. Crural plates. o. Ovarian mai-king-s. 



j. Cardinal process. v. Vascular mai-kings. 



c. Crura. 



DALMANELLA, nom. nov. 



Page 20.O. 



Orthis emacerata, Hall. 



¥ig. 1. The central cardinal portion of the interior of a bi'achial valve; showing' the processes and 



muscular imprints. X 3. 

 Fig. 2. The exterior of a bi'achial valve. 



Hudson River g-roup. Cincinnati, Ohin. 

 For furthei' illustration, see Palaeontology of Ohio, Volume I, plate viii, figs. 1, 2. 



Orthis Meeki, Miller. 



Fig. 3. The interior of a brachial valve ; showing the cardinal pi-ocess, crura and muscular scars. The 

 ajiparent impressions in the umbo-lateral regions are due to abnormal thickening of the test. 

 X 2. 



Hudson River group. Spring Valley, Minnesota. 



Orthis Stonensis, Safford. 



Fig. 4. Profile of a specimen with \-alves conjoined. X 2. 



Fig. b. A view of the pedicle-valve of the same specimen ; showing the alternating, fasciculate character 

 of the radiating strife. X 2. 



Orthis suBiEQUATA, Conrad. 



Fig. 6. A view of the bi'achial \ahe of the oiiginal siieciinen ; showing the area and foraiiien of the op- 

 posite valve. 

 Figs. 7, 8. Profile and eaniinal views of the same. 

 Fig. 9. The ai'ticular and muscular ai'ea of the brachial valve. X 3. 

 Figs. 10, 11. Interiors of the pedicle and brachial valves. 



Trenton horizon. Mineral Point, Wisconsin. 

 Foi' further illustration, see Palfeontology of New York, Volume I, plate xxxii, fig. 2. 



Orthis perveta, Conrad. 



Fig. 12. View from the brachial \'al\e of the original specimen. 

 Figs. 13, 14, Brachial and profile views of a larger individual. 



Trenton horizon. Mineral Point, Wisconsin. 

 For further illustration, see Palseontology of New Yoi'k, Volume I, plate xxxii, tig. 5. 



Orthis elegantula, Dalnian. 



Figs. 15, 16. Opposite sides of the same imlividual ; showing the form of the species as occurring at this 



locality. 

 Fig. 17. The interior of a pedicle-valve, somewhat enlarged. 

 Fig. 18. The intei'ior of a brachial valve ; showing the muscular impressions and articular jjrocesses. X 2. 



Niagara group. Waldron, Indiana. 

 Fig. 19. Cai'dinal view of the central poi'tion of the brachial valve ; showing the composition of the cardi- 

 nal process, the great elevation of the crural plates and crura, and their furrowed or crenulated 

 outei' walls. X 3. 



Upper Silurian limestone. Island of Gotland. 

 For further illustration, see Davidsok, Silurian Brachiopoda, pi. xxvii, figs. 1-9 ; Hall, Twenty- 

 eighth Rept. N. Y. State Mus. Nat. Hist., pi. xxi, figs. 11-17. 



