386 W. < . KNIGHT — JURASSIC ROCKS OF SOUTHEASTERN WYOMING 



Comptonectes sp. 

 Comptonectes bellistriata, Meek. 

 Paeudomorwtis curia, Hall. 

 Pseudomonotis orbiculata, Whitfield. 

 Modiola sp. 

 Pinna sp. 



Grammatodon inorncUus, M. & H. 

 Astoria packardi, White. 

 Astoria, sp. 



Tancredia cf. inornata, (M. & H.) 

 Whitfield. 



Pleuromya svbeompressa, Meek. 

 Goniomya montanaenbU, Meek. 

 Belenntites densus, M. & H. 

 Cardioceras cardiformis, M. & H. 

 ( 'ardioceras cardiformis, var. distans, 



Whitfield. 

 Cardioceras sp. 

 Cardioceras t sp. 



Peniacrinus asteriscus,* M. & H. 

 Gryphse.a nebrascensis, M. & H. 

 Dentalium subt/uadratus, Meek. 



Vertebrates 



But few vertebrates have been found in this stage, and Baptanodon is the most 

 common. The following species of Wyoming reptiles have been reported : 



Baptanodon discus, Marsh. Megalneusaurus rex, Knight. 



Baptanodon natens, Marsh. 



In the collection of the University of Wyoming there are two new Plesiosaurs 

 which have not been described and an Inchthyosaur which resembles the genus 

 Ichthysaurus of Europe, it being very much larger than Baptanodon. The Plesio- 

 saurs are small and appear to resemble Liassic forms of Europe. 



The Jurassic fishes recently discovered in the Black hills by N. H. Darton and 

 described by Doctor C. R. Eastman in all probability belong to the Shirley stage. 

 These species are 



PholidopKorus americanus, Eastman. 



miopsis dartoni, Eastman. 



Doctor Eastman,! in describing P. americanus, says " that it is not far removed 

 from P. beclwi, Agassiz, from the lower Lias." 



EXTENT OF SHIRLEY STAGE 



The Shirley stage varies in thickness from a few to nearly 200 feet, 

 and thickens in its north and western extension from southeastern 

 Wyoming. The limits of this stage are not as well known as the Como, 

 but extends from the Miser anticlinal north and eastward to the Black 

 hills and to the westward. It is possible that the Ellis stage of the 

 Yellowstone park may be in part the Shirley. Since the Shirley stage 

 is not known in southern Wyoming and northern Colorado, it is evi- 

 dent that the Triassic had been elevated above the sea during the depo- 

 sition of this series, and that it was again submerged at the commence- 



* only last summer I discovered the head of Peniacrinus asteriscus. This species was described 

 from if* column by Professor Meek in 1858. Until the present discovery nothing of the head has 

 been known. Professor (lark, of Johns Hopkins, will shortly figure and describe this, the only 

 American Jurassic Pentacrinus. 



\- Bull. Geol, So<-. Am., vol. in, p. 4n.">. 



