"ARK] PENTACRINUS WIU'rEI. 27 



scribed, should be coiisidorod sncli. The re(Mitei-in,u' ano-les arc nuich 

 too deep. Unrortniiately there is no side view of the phites. 



Related forms. — This species is wliolly unlike the other American 

 forms. lu the first phiee, it is mueli sniaHei- than P. Wltitei, and /*. 

 Brya)ii iunl has ii distinctly ditterent form from P. Whiiei with which 

 it has been hitherto confounded. In P. W/iitei the reentering angle is 

 made deeper an<l of difierent shai)e. Likewise tlie crenulations of the 

 petaloid area of the joints are dirt'erently arranged. The Joints them- 

 selves are also relatively much thickei-. 



Locality and (/eolof/ical horizon. — Keported by Meek and Haydeu' 

 "associated with other Jurassic fossils from the southwest base of Black 

 Hills, and opposite Ked Buttes, Nortli Platte river," the former in Da- 

 kota, the latter in Nebraska. In the Check List of Invertebrate Fossils 

 from the Jurassic, Meek also mentions Idaho and Colorado. Peale men- 

 tions the occurrence of specimens in Idaho. 



CoUection. — U. S. National Museum. 



PENTACRINUS Whitei Clark. 



Plate III, Figs. 4«^c. 



PentacrinUes asierisciis White, 1875. U. S. Geog. Survs. west of 100th Meridiau, vol. 



4, 1875, p. 162, PI. XIII, Figs. Ga-h. 

 Wentacriniten asteriscus ( ?) Hall and Whitfield, 1877. U. S. Geol. Expl. 40th Parallel, 



vol. 4, pp. 280, 281, PL vi, Fig. 16. 

 'i PentacrinUes asteriscus Whitfield, 1880. Geology of Black Hills of Dakota, p. 345, 



PI. Ill, Figs. 1, 2. 



Determinative characters. — Calj'x Avautiug. Column composed of 

 large, thin, pentagonal joints that possess deep reentering angles. 

 The crenulated ridges of the suture have a petaloid arrangement. Col- 

 umn perforated by central canal. 



Dimensions. — Column: breadth of joint, ^ to ^ inch; length of joint, 

 7^0 inch. 



Description. — In the volume upon i^aleontology of the quarto pub- 

 lications of the U. S. Geological Surveys West of the One- Hundredth 

 Meridian, Dr. White figures and refers a form to Pentacrinites asteriscus 

 Meek and Hayden, that belongs evidently to another species, A com- 

 parison bj^ the writer of the specimens ligured by Meek and Ilaydeu 

 and by White .shows that the differences are too great to permit 

 their reference to the same species. The name P. Whitei is there- 

 fore suggested for the new form in honor of the distinguished scientist 

 who has done so much to advance our knowledge of American 

 Mesozoic geology and paleontology. As with P. asteriscus only por- 

 tions of the column of P. Whitei have been discovered. The outer side 

 of the column is furrowed by deep reentering angles producing live 

 prcmiiuent ridges at the salient angles. The joints are relatively thin, 

 with rounded edges, so that the column does not appear compactly 



• Paleontology Upper Missouri, p. 67. 



