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. g. — 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 Palaeontogeny and Phylogeny ; all the other figures on this plate are 

 original. Drawings by Frances R. Smith. 



