412 ALLAN' HAXCOCK PACIFIC EXPEDITION'S VOL, 3 



PLATE 57 



All Figures Natural Size 



Figs. 11-16 Lithothamnion atistralf, various forms all occurring in 



the same collection, Dawson 593a. 



Figs. 17-18. Porolifhon sonorcnsis, sterile examples, Dawson 226a. 



Fig. 19. Porolifhon sonorcnsis, tetrasporic example, Dawson 465. 



Fig. 20. Lithophylluni Jrcipiins, Dawson 479, 



