420 ALLAX HANCOCK PACIFIC EXPEDITION'S VOL. 3 



PLATE 61 



Fig. 1. I.ilhdphyllum lithopliylloiJi'S, photomicrograph of a section 

 of a tetrasporic crust, Dawson 250, x 50. 



Fig. 2. Porolitlio?i sonorensis, photomicrograph of a section of a 

 tetrasporic crust of the type, Drouet & Richards 3383, x 120. 



