202 



CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



Text- Fig. i. 



Fig. I. Diagram showing the condition of the radial branches in {a) BibiocepJiala 

 grandis, (V) Bibiocepluila. comstocki, (c) Bibiocephala elegantuhis, {d) Bibiocepliala doanei, and 

 (e) Philorus bilobata. These five species form a series in which radius^ proceeds from 

 a condition in which it is free for almost its whole length to a condition of complete 

 coalescence, i. e. disappearance. 



