PROTREMATA (Pack 245) 



Figure 13. — Dorsal protegulum and early nepioiiic growth-lines 

 of Plectamboniles segmentina Angelin. X 80. Upper Silurian, Gotland, 

 Sweden. 



FiGUUK 14. — Dorsal protc^uliuu of Clioncles sciluUis llall. X 80. 

 Hamilton Group, Thedford, Ontario. 



FiGUiiE 15. — Ventral protegulum of C/ionetes firaniili/crus Owen; 

 showing pedicle-notch. X 80. Coal Measures, Manliattan, Kansas. 



FiGUKK Ui. — Nepionic stages of ventral valve of Orthothetes elegans 

 Bouchard. X "-5. (Compare with figure 12 of Acrolhele.) Devonian, 

 Ferques, France. 



Figure 17. — Nepionic stages of Stro/iheoilontd j)('r/il(nin Conrad; 

 showing pedicle perforation, deUidium, and liiuge-area. X '-5. Ilaniii- 

 ton Group, Falls of tlie Ohio. 



FiGUUE 18. — Ventral nepionic stage oi Leptana rhonihohlalh Wilckens. 

 X25. 



Figure 19. — Profile of the same. X 25. 



Lower llelderbei-g Group, Albany county, New York. 



Figure 20. — Hinge of a specimen 2 mm. in length ; showing deltid- 

 ium and hinge-area. 



Figure 21. — Ventral view of specimen having same dimensions; 

 shov^ring nepionic and neanic stages, and relative proportions of pedicle- 

 opening and shell at this stage. Niagara Group, Waldron, Indiana. 



Figures 20 and 21 are taken from " Develojiment of Some Silurian 

 Brachiopoda," Mem. N. Y. State Museum, vol. i, no. l,pl. ii, figures 2, 12, 

 1889. 



TELOTREMATA (Pages 245, 24G) 



Figure 22. — Ventral view of young Kraussi)ia (Megerlina) Lavmrcki- 

 ana Davidson ; showing jirotegulum and early nejnouic stages. X 80. 



Figure 23. — Dorsal view of same; showing dorsal protegulum and 

 pedicle-o])ening in ventral valve. X SO. 



Recent, Port Jackson, Australia. 



Figure 24. — Dorsal view of beaks of young TereJiratulind srpten- 

 trionalis Conthouy; showing dorsal protegulum and pedicle-opening in 

 ventral valve. X 80. Recent, I'^astport, Maine. 



Figures 2.5-28. — Diagrammatic representation of ventral areas; 

 showing progressive development of deltidial plates. 



Figure 25 is without plates, as in ventral area of figure 23. Figure 26 

 shows two triangular plates, which unite by symphysis in figure 27, 

 making an elongate pedicle-opening. In figure 28 the pedicle jierforation 

 is sub-circular and truncates ventral beak. This series corresponds 

 essentially with that shown in Rhi/nchotretn cuneata Dalmau. in "Develop- 

 ment of Some Silurian Brachiopoda," loc. cil., pi. iv. figures 10-22. 



