1=^4 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



EXPLANATION OF THE FIGURES. 



Plate XVII. 



Lytoceras alamedense, sp. nov. 



Fig. I. Cross-section, early adult stage; diam. 8 mm., ten times enlarged, 

 four and one-eighth coils. 



Fig. 2. Spiral, late adolescent stage, diam. 3.9U nun., two and three-quar- 

 ters whorls, thirteen times enlarged. 



Fig. 3. Front outline of the same, diam. 3.90 mm. 



Fig. 4. Side view, early adult stage, diam. 7.50 mm., three and three-quar- 

 ters coils, seven times enlarged. 



Fig. 5. Front outline of the above (7.50 mm.). 



Fig. 6. Spiral, adult, diam. 14.5 mm., five whorls, four times enlarged. 



