PLATE XXXIV 

 TORNOCERAS (Pages 437-439) 



Figure 1. — Protoconch ; showing first septum with lateral edges 

 broken. X 18. 



Figure 2. — Side view of preceding. X 18. 



Figure 3. — Ventral view of protoconch with one attached air-cham- 

 ber; showing siphonal caecum. X 18. 



Figure 4. — Side view of first whorl. X 18. 



Figures. — Ventral view of preceding; showing development of 

 ventral lobe. X 18. 



Figure 6. — Transverse section of two whorls near the proto- 

 conch. X 18. 



Figure 7. — Ventral side of protoconch, retaining the shell. X 18. 



Figure 8. — Ventral side of specimen with first chamber; showing sur- 

 face ornaments and indication of siphonal casoum. X 18. 



Figure 9. — Profile of same. X 18. 



Figure 10. — Surface ornaments on a specimen consisting of a single 

 whorl. X 18. 



Figure 11. — Four strife from the second whorl of a specimen ; show- 

 ing funnel sinus. X 18. 



Figure 12. — Vertical section ; showing septa and air-chambers. X 18. 



Figure 13. — Outline of a half -grown specimen, x 3. 



Figure 14. — A series of developed septa beginning with the first ; 

 showing gradual inception and formation of lobes and saddles to the 

 adult period represented hy j. a, b, c, d, represent the 1st, 2d, 3d, and 

 4th septa, while e and /represent the 7th and 8th, respectively. X 9. 



Specimens in Yale University Museum, from the Hamilton Shales of 

 Wende Station, New York, except specimen figure 13, which is from 

 18-Mile Creek, New York. 



