EXPLANATION OF THE FIGURES.* 



PLATE III. 

 Schloenbachia nov. sp. aff. S. chicoensis TRASK. 



Fig. I. Cross-section, diameter 6.25 mm., four whorls, seven 

 and a half times enlarged, showing the embryonic protoconch in 

 the centre, P. 



Fig. 2. Cross-section, adult, diameter 22.25 mm., six whorls, 

 one and three quarter times enlarged. 



Fig. 3. Protoconch and the first six septa of the attached coil, 

 drawn as if unrolled, fifteen times enlarged. 



Fig. 4. Larval stage, diameter .68 mm., fifteen times enlarged, 

 corresponds to the Carboniferous genus Glyphioceras. 



Fig. 5. Larval stage, diameter .64 mm., showing septa from 

 the third to the tenth, fifteen times enlarged. 



Fig. 6. Septa in Glyphioceras stage, diameter .75 mm., seven 

 eighths whorls. 



Fig. 7. Larval stage, transitional from Glyphioceras to Gastrio- 

 ceras, diameter 1.20 mm., one and a half whorls, seven and a half 

 times enlarged. 



Fig. 8. Septa in Gastrioceras stage, diameter 1.70 mm., two 

 coils. 



Fig. 9. End of larval stage, corresponds to the Carboniferous 

 genus Paralegoceras, diameter 2.25 mm., two and a quarter whorls, 

 seven and a half times enlarged. 



Fig. 10. Septa in Paralegoceras stage, diameter 2.50 mm., two 

 and a half coils, end of larval stage. 



Fig. II. Septa in Para-Styrites stage, fifteen times enlarged, 

 diameter 3.80 mm. (early adolescent). 



Fig. 12. Adolescent stage (Para-Styrites), four coils, diameter 

 5.60 mm., seven and a half times enlarged. 



Fig. 13. Septa at diameter 6.40 mm., fifteen times enlarged, 

 three and three fourths whorls (middle adolescent). 



* Figs. 1-4 from J. P. Smith, Journal Geol., vol. v, No. 5, Comp. Study 

 of Palasontogeny and Phylogeny ; all the other figures on this plate are 

 original. Drawings by Frances R. Smith. 



