54 SMITHSONIAN INSTITUTION 



from that of the unaltered plates ; the latter may often be seen when exposed 

 by cleaning in a part covered by matrix, so that the two kinds of surface 

 appear in the same specimen. See, for example, the specimen of S. pratteni 

 figured on Plate VIII, figures 2a, b. 



Free specimens of the bulbous roots are not abundant at the pyburnensis 

 locality ; the few obtained are much smaller than those associated with pratteni. 

 Hall described Camarocrinus saffordi and C. clarki upon material from this 

 region, but as there is no evidence to indicate with which of several calices 

 either of them is associated, the names cannot be utilized for any of these 

 species. 



Types. — In the author's collection. 



Horizon and locality. — Helderbergian ; Ross limestone of the Linden 

 formation, in blue limestone and associated cherty beds for 30 or 40 feet up 

 from the water's edge, Pyburn's Bluff, Hardin County, Tennessee. 



7. Scyphocrinus ulrichi (Schuchert) 

 Plate IX, figs. 2a, b 



1903. Camarocrinus ulrichi Schuchert; Amer. Geologist, vol. 32, October, p. 239. 



1904. Camarocrinus ulrichi Schuchert; Smithson. Misc. Coll., vol. 47, pp. 263, 271, pi. 40, 



figs. 6-8; pis. 41-43, and text-figs. 43, 44. 



Calyx large, ovoid, the larger end below, spreading by a very broad angle 

 from the base; widest about the second range of interbrachials, and con- 

 tracting slightly from there to near the zone of arm-bases. Plates flat, or low- 

 convex, some with pustulose center; lower interbrachial areas rather unevenly 

 and obtusely swollen, posterior area the largest. Secundibrachs relatively 

 narrower and longer than in 5". pratteni, and apparently less than 10 in number. 

 Arms and stem unknown. 



Dimensions of type specimen: Height of calyx, 62 mm.; greatest width, 

 50 mm. ; width toward arm-bases, 43 mm. 



This species is represented by a single calyx, found in the talus of beds 

 containing numerous Camarocrinus, to which Mr. Schuchert has given the 

 above specific name. As many of these are very large, it is assumed that they 

 appertained to individuals of this species rather than of the smaller S. gibbosus. 



Owing to the surface condition of the rather flat plates, it is difficult to 

 identify the interbrachials in some places, but it is evident that the modification 

 of the lower pinnules due to fixation has proceeded much farther in this than 

 in the other species — so far in fact that all semblance of pinnule arrangement 

 is lost. At the same time there is an entire absence of the surface sculpture 

 produced by ridges or pits, so that the conspicuous pavage of the other species 

 is absent here. The secundibrach series leading to the first arm bifurcation is 

 also much less distinctly rounded. 



