350 SMITHSONIAN INSTITUTION 



Protaxocrinus virginiensis n. sp. 



Plate XLV, fig. 12 



Of the same habitus as the last species, but with thinner and more rapidly 

 tapering" arms. 



The species is proposed for a well-preserved specimen from a later horizon than the 

 preceding. The character given for its separation is not very decisive, but considering the 

 difference in horizon and locality, it is probably a good species. Some of the Helderbergian 

 crinoids have a strong general similarity to those of the late Niagaran, but they are in no 

 case actually identical. 



Type. The author's collection. 



Horizon and locality. Devonian, Keyser formation of the Helderbergian ; Keyser, West 

 Virginia, associated with Pycnosaccus tenuibrachiatus. 



Protaxocrinus interbrachiatus (Angelin) 

 Plate XLV, figs. 13-16 



Taxocrinus interbrachiatus Angelin, Icon. Crin. Sueciae, 1878, p. 8, pi. 20, figs. 9, 10. 



Taxocrinus (Gnorimocrinus) interbrachiatus, Wachsmuth and Springer, Revision Palaeocrinoidea, pt. I, 



1879, p. 50. 

 Protaxocrinus interbrachiatus, Springer, Jour. Geology, XIV, 1906, p. 515. 



A large species. Crown robust, elongate ovate, widest about IIIBr 3 , where 

 the interbrachials pass into the tegmen. Height to width of crown, 2.1 to 1 ; 

 of calyx at top of I Ax, i to 1.4; spread of calyx from base, 1 to 2.4, chiefly above 

 level of BB. Lateral margins of brachials in lower half of rays angular, form- 

 ing sharp, conspicuous buttresses with which the perisome connects at their 

 inner margin. Arms broadly rounded or sometimes slightly angular, orna- 

 mented distally with longitudinal ridges on each brachial. Base flush with top 

 columnal, and calyx expanding suddenly. Height of crown of large specimen, 

 40 mm. ; width, 16 mm. ; width of base, 5 mm. 



IBB low, slightly visible above the column. BB forming a funnel continu- 

 ous with column. RR the largest plates of calyx, causing a rather pronounced 

 expansion at their level. Anal tube strong, with first two or three large plates 

 attached to r. post. ray. RA smaller than corresponding RR. iBr consisting of 

 one to three well-defined plates followed by a profuse development of perisome 

 in the first and second axils. IIBr 4 or occasionally more. IIIBr 7 to 9 outer, 

 5 or 6 inner; IVBr 13 to 15 outer, 8 to 10 inner. Arms strong, tapering slowly, 

 infolding above the fourth bifurcation. Brachials generally wider than high, 

 and sutures for the most part straight, without distinct sinuosity. Column 

 strong, with proximal columnals as broad as the base; gradually diminishing 

 in width downward. 



The most striking characters of this Swedish species are the lateral buttress-like angu- 

 larities of the brachials, and the profuse development of plated perisome as far as the second 

 axil. These are finely shown by the figures made from various specimens in the museum at 



