SILURIAN SYSTEM: AGE OF INVERTEBRATES. 



299 



Fig. 275. Fig. 276. Fig. 27! 



Figs. 269-279.— American Cambbian Fossils (after Walcott and Whiter 269. Protypns Hitch- 

 cocki, x 2. 270. Zacanthoides tvpiealis. x 2. 271. Agnostne interetrictns. 272. Fordilla irny- 

 ensis 273 Orthisina transversa. 274. Kutorgina pannnla— o, front view: a, side view. 2,o. 

 Olenellus Gilbert! 276. Diplograptus simplex. 277. Hyolithes primordialis. 278. Lmgulella 

 celata. 279. Obelella crassa. 



