PROTY. 



784 



Protypus senectus. {Bathyurus senectus^ Billings, 1861, 

 I ^. Geol. Vt. I, 953, figs. 359, 360; Pal. Foss. I, 

 '• ^'* page l^^-. Geol. Can. 286, figs. 298 a, h. Also 

 Bathyurus parvulus^ Billings, 1861, Geol. 

 Vt. II, 953. Compare also Corynexochus 

 spinulosus, Angelin, of Sweden.) Wal- 

 cott, Bulletin No. 30, U. S. G. 8. page 213, 

 plate 31, fig. 2, flattened; 2 a, compressed 

 ^^ sidewise ; 2 b, 2 c, tails (pygidia) found with 



^h 



'Xj "" the heads. Lower Cambrian ( Oeorgian) 



slate, at Parker's quarry, Vt. ; near Swan- 

 ton, Vt., and in Labrador. Z. G, 



IJLGe, 



PI. %l. 



Psammodus angularis, Newberry and Worthen, Geo. Sur. 



111., Vol. 2, 1866, page 

 107, plate 11, figs. 2,2 «, 

 2J, upper surface, side, 

 and end of fish tooth. 

 (See other figures in 

 Vol. 7, 1883, pi. 19, figs 

 1 <^ to 2 /. omitted.) The pores of the surface diiFer from those 

 of P, rugosus in being relatively larger, but round, distinct 

 and never confluent. Chester, 111., in Chester limestone. XI. 



Psammodus ceelatus, St. John and Worthen. Geol. Sur. 



r:r.-:^—%A :r-'^"S 7, 1883, 



— vi-' 



page 217^ 

 C^eolJUinois^Vo/:rj^%Z/P/ate/8. plate 18, 

 fig. 1 ^, fish-tooth triturating surface ; 5, c, d.> outside, binder, 

 front edges ; e^ profile section. Iowa. St. Louis limestone. XI. 



PsammLOdus crassidens. St. John and Worthen. Geol. 

 111., Vol. 7, 1883, page 218, plate IS, selected figs. 2 a, a small 

 tooth, crown worn smooth; 6, c, d^ e, inner, outer, hind and 

 front borders; 3 ^, shorter tooth preserving traces of roughness 

 of crown; 5 (Oj, large entire tooth, with crown 'worn smooth, 

 and prominent base rim outside ; 5, 5, <?, d^ e. articular, outer. 



