CONTRIBUTIONS TO PALiEONTOLOGY. 

 Fig. 4. Fig. 5. • Fig. 6. 



57 



Fig. 4. Retzia (Terebratula) adrieni, copied from the figure of Davidson : The type of 



E.ETZ1A. 



Fig. 5. Retzia (Terebratula) ferita.* 



Fig. 6. . . . . ferita, showing the internal spire on one side (enlarged) . 



Fig. 7. 



Fig. 8. 



Fig. 9. 



Fig. 7. Trematospira perforata : Enlargement of a part of the shell, showing the perforation 



of the beak and the area below, with umbo of the dorsal valve. 

 Fig. 8 & 9. Trematospira muUistriata : Ventral and front views of a large individual. 



Fig. 10. 



Fig. 11. 



Fig. 10. T. muUistriata : A ventral valve from which the dorsal valve has been removed, 



showing the spires as they appear on the polished surface of the stone. 

 Fig. 11. Dorsal and front views of T. costataA 



In the species whicli I have designated as Rhynchospira, we have 

 uniformly longitudinally ovate or subglobose forms, which are marked by 

 regularly rounded or somewhat flattened plications; one, two, or more of 

 which, in the centre, are always smaller than the others, though there is 

 usually no defined mesial fold or sinus. The front is often truncated, and 

 sometimes a little sinuous. 



The general form and surface-characters of the species of this genus 

 resemble those of Retzia serpentina, R. vera and it. verneuili ; but the 

 smaller mesial plications are distinctive, and the hinge-structure and area 

 are conspicuously different. The extremity of the beak is perforate, and 



* This figure is about twice as large as any specimen of R. ferita which I possess. 

 T These figures are from the 12th Rep. on the State Cabinet, and Vol. iii, Pal. N.Y. 



[Senate, No. 115.1 8 



