PLATE 34. 
Fig. 1-6. Rhynchonella? bialveata. 
1 a, b. Dorsal and ventral views of a small individual. 
2 a, b, c. Dorsal, ventral, and profile views of a less elongate form. 
3 a, b, c. An individual having the plications nearly equal, and showing scarcely any indica¬ 
tion of a sinus in front. 
4. An enlarged figure of the same species. 
5 a, b, c, & 6 a, b, c. Rhynchonella semiplicata? 
The forms here figured closely resemble the R. semiplicata of the Pentamerus limestone; being a 
little more rotund, and deeply sinuate. This form is extremely rare in the shaly limestone of the 
Lower Helderberg group. 
Fig. 7 & 8. Rhynchonella inutilis. 
7 a, b. Ventral and profile views of a small individual. 
8 a, b. Ventral and front views of a more rotund form. 
Fig. 9 - 19. Rhynchonella transversa. 
9-14 a, b. c. A series of individuals showing a regular gradation in size, with a gradually 
increasing depth of sinus. 
15 & 16 a, b, c. Individuals having a more strongly defined sinus and mesial lobe; a single 
individual having but two folds in the sinus. 
17 - 19 a, b. Rhynchonella transversa? var. 
These forms present some differences of character from those referred to the species proper; being 
somewhat more circular, and the lateral plications a little curving. 
Fig. 20 & 21. Rhynchonella rums. 
20 a, b, c. Ventral, front and profile views. 
21 a, b. Profile and front view of a similar form, which varies in some respects. 
Fig. 22. Rhynchonella planoconyexa. 
22. A cast of the dorsal valve, preserving the shell upon the margin. 
