318 SMITHSONIAN INSTITUTION 



The extreme narrowness of the interbrachials is a striking feature of this species, being 

 equally pronounced in both type specimens. The inf rabasals are only exposed in one speci- 

 men, and there they are almost entirely resorbed. The base of the principal specimen is 

 partly covered by a fragment of the upper stem ossicle, which conceals the unresorbed part 

 of the infrabasals and two of the basals (PL XL, fig. 4a). This fact led to the supposition 

 that the genus was entirely exceptional for this group in being monocyclic and having but 

 four basals. The concealed part of the infrabasals can be seen from the interior, clearly 

 enough in the specimen but dimly in figure 4&, and it is plain that they are in the same condi- 

 tion as in E. rofei (fig. yb). 



Types. In the British Museum, Nos. E6983 and E6984. 



Horizon and locality. Lower Carboniferous, Mountain limestone; Bolland, Yorkshire, 

 England. 



Euryocrinus tennesseensis n. sp. 



Plate XL, figs. 6a-c 



A medium-sized species. Crown short, low, and broadly spreading; height 

 about equal to width at lower IIIBr. Calyx low and broad, height to width at 

 top of I Ax, about 1 to 3.4; spread from base, 1 to 2.1 ; side outline convex. Arms 

 broadly convex to the third axillary and in close contact, margins nearly straight 

 and not raised; all brachials very short and wide; sutures arcuate; iBr few, 

 large. Surface finely pustulose. . Dimensions of type : Crown, 32 mm. high by 

 about 32 wide; base, 8 mm. ; calyx to top of I Ax, 5 mm. high by 17 wide. 



IBB within BB, covered by column. BB almost entirely within shallow 

 column facet, only very low obtuse points appearing beyond the column. Post, B 

 very large, rising higher than R. RR and IBr short, about three times as wide 

 as long. IIBr 3; IIIBr 4 or 5 inner, 7 or 8 outer, with another bifurcation on 

 the outer ramus at about the 9th plate, after which the arms infold. Anals in 

 single series of 3 or 4 plates; iBr 1 large, followed by 1 or 2 small ones, with a 

 small illBr sometimes present; brachials in close contact above all iBr. 

 Column large, with very thin proximal columnals, tapering from the^ calyx. 



This species is interesting as marking the occurrence of this rare genus in the American 

 equivalent of the English Lower Carboniferous to which it belongs, and it adds one more 

 important fact in confirmation of the correlation of the formations at the base of our Lower 

 Carboniferous with the crinoid-bearing Mountain limestone of England and Belgium. It has 

 been found in several localities, mostly in imperfect fragments. The type, from the lower 

 beds at White's Creek Springs, Tennessee, is considerably flattened and distorted, but clearly 

 shows all the essential characters. Owing to this flattening the arms appear less convex than 

 in most of the specimens. Comparison with the English species can only be made as to the 

 calyx ; the differences are not great, being chiefly in the interbrachial plates which are here 

 decidedly larger and a more definite feature of the calyx wall than in E. concavus, while much 

 more restricted vertically than in E. rofei. The pustulose surface, in which this form may 

 somewhat resemble E. granulosus, is scarcely more than a fine granulation ; and it lacks the 

 large basals of that species. 



Type. Author's collection, associated with several fragments from the different localities. 



Horizon and locality. Lower part of the Lower Carboniferous, in the Knobstone shales 

 and limestones called the New Providence beds, equivalent to some part of the Lower Bur- 



