TRENTON PEEIOD. 65 



Graptolithus (Diplograptus) pristis Hall, (?). 



Plate IV, fig. -2 a aurt h. 



? Prionotus pristis Hisingor, 1837, Letbsea Suecica, 114. 

 Graptolithus pristis Hall, 1847, Paleontology of New York, i, 265. 



Stipe flattened; outline of the broader sides sublinear or very elongate- 

 oblanceolate ; cells moderately large, their- iipper sides or apertures being 

 transverse and the outer sides sloping directly downward and inward gives 

 the edges of the stipe a distinctly dentate appearance as it is compressed 

 in the shale. Like related species, this has a slender thi-ead-like axis passing 

 longitudinally tlu-ough its middle and extending beyond the distant cells. 



In my preliminary report on these collections, this species was con- 

 founded with G. quadrimncronatus Hall? ; fragments of the two species 

 being mingled in the same pieces of shale. This circumstance modified 

 my description of that species, but the correction is made in this report 

 from the study of more perfect specimens. Our examples show some 

 differences from the typical forms of G. pristis, but they correspond so 

 nearly with them that I do not at present feel waiTanted in proposing a 

 separate specific name. 



Position and locality. — Shales of the Trenton period, probably of the 

 Utica epoch ; five miles north of Belmont, Nevada, where it is associated 

 with the two species last described, and also with the following one. 



Graptolithus quadrimucronatus Hall (?). 

 Plate IV, fig. 1 a aud h. 



Graptolithus quadrimucronatus Hall, 1865, Geol. Surv. Canada, decade ii, 144. 

 Graptolithus qiiadrimucronatus ? White, 1874, Exp. & Surv. west lOOtli Merid., Prelim. 

 Eep. Invert. Foss., 13. 



Stipe quadrilateral, transverse section oblong, gradually but slightly 

 increasing in diameter from the proximal or basal end to about midlength, 

 where the maximum size is reached; cells opening on the two narrower 

 sides of the stipe ; their apertru'es opening obliquely upward, being naiTow, 

 transverse, four-sided slits of uniform size, about half as wide as the inter- 

 spaces, their length equaling the full diameter of the stipe; the outer 

 comer of each cell-aperture provided with a minute projecting point. 

 5f 



