(UtAPTOLITES OF NEW YORK. I'AUT 1 Hi 



Dawsonia tridens Gurley 



Plate ]7, tigure 18-20 



Dawsouia tridens Gurlej. Jour. Geol. 1896. 4:88, pl.5, fig.5 

 Dawsonia tridens Ruedemann. N. Y. State Paleontol. An. Eep't. 1902. 

 P..556 



Description. Rliabdosonie sliortl}'' and asymmetrically fusiform in out- 

 line; about 3 mm long (3.4 mm maximal length observed), 1.1mm wide, drawn 

 out at botli extremities into blunt mucros. A median groove, Avhicli becomes 

 most distinct at the atbecal extremity, connects the mucros. On one side 

 there are two or three oblique incisions Avhich produce acute denticles of the 

 appearance of thecae. Other side more convex, with entire margin. Sub- 

 stance chitinous Q), thin. 



Position and localities. Common at the Deep kill in graptolite beds 1 

 and 2 of the Tetragraptus horizou. Gurley obtained his types from the same 

 horizon at Point Levis. 



Reviarhs. Our material agrees in most particulars with the description 

 and figure given by Dr Gurley. We -were, however, unable to discern the 

 " pustules '' observed by him at the inner ends of the incisions ; but noticed 

 sometimes a widening of the incisions at this place [fig.lSJ. The groove, 

 described by the same author, as occurring at the blunter extremity, crosses 

 our specimens longitudinally. As Gurley remarks, this species resembles in 

 outline and size most closely D. acuminata Nicholson. The latter, 

 however, has one extremity rounded and can by this feature be readily 

 distinguished. 



Dawsonia monodon Gurley 



Plate 17, figure 21-26 



Dawsonia monodon Gurley. Jour. Geol. 1896. 4:88, pl.5, fig.4 

 Dawsonia monodon Ruedemann. K Y. State Paleontol. An. Rep't. 1902. 

 p.554, 556 



Description. Rhabdosome elongate rhomboidal in outline ; about 10 mm 

 long and 3 mm wide ; of the two extremities of the major axis one (proximal 

 one?) rounded, the other acutely tapering; the two lateral extremities 

 extended into shorter, downwardly directed mucros. The acutely tapering 



