APPENDIX E. — PAL^ONTOLOar. 409 



BRACHIOPODA. 



Terebeatula subtilita. 



Plate II. Fig. 1 ab, 2ab. 



Gibbous, obovoid; valves nearly equal, convex; beak of the 

 dorsal valve elevated, incurved, and perforated at the apex ; a 

 mesial depression commencing just below the centre and extending 

 to the front, which is produced and elevated, iBlling a broad sinus 

 in the ventral valve ; surface marked by strong concentric striae, 

 or lines of growth, with faint, often almost imperceptible radiating 

 striae. 



Fig. 1 a, a young individual. 



Fig. 1 b, an individual of the ordinary size and form. 



Fig. 2 a, a more gibbous form. 



Fig. 2 b, profile view of the preceding. 



Fig. 2 c, front view of the same. 

 Loc. Missouri River, near Weston. 



Spirifer hemiplicata. 



Plate II. Fig. Sab. 



Shell gibbous ; ventral valve more elevated, beaks nearly equal ; 

 entire surface marked by finely radiating strata ; each valve with 

 about three plications on each side of the mesial sinus and eleva- 

 tion, which plications extend halfway from the base to the beak, 

 leaving the upper half of the shell marked only by fine striae; 

 anterior portion of the dorsal valve produced in a long extension, 

 which fills a deep angular sinus in the ventral valve. 



Fig. 3 a, view of the dorsal valve, which, from distortion, shows 

 the beak of the ventral valve projecting above it. 



Fig. 3 b, front view of the same specimen. 



Loc. Missouri River, near Weston. 



Spirifer octoplicata? 



Plate IL Fig. 4 a b. 



The specimens figured appear to be young individuals, and may 

 probably belong to this characteristic carboniferous species. 



Fig. 4 a, this specimen has sufi'ered from lateral pressure, caus- 

 ing an unnatural extension of the beak. 



