l68 SMITHSONIAN INSTITUTION 



plate connecting with IBr, either followed by perisome direct, or by small plates 

 at either side as in the anal area. IBr 2, low, filling distal face of R; height of 

 B to R to IBr as 3-5 : 3.5 : i. IIBr 2; IIIBr 3 or 4. Arms angular to second 

 bifurcation, shortly beyond which they infold. Column large, long, tapering 

 very gradually to a fine point ; composed of strong, rounded columnals, with 

 slightly shorter and narrower ones interposed for a short distance from the 

 calyx ; beyond this they become nearly equal in size, about two-thirds as long as 

 wide and strongly rounded, resembling a string of beads; near the distal end 

 they lose their convex rim, become straight and much elongated, nearly twice 

 as long as wide. 



This species was described by Professor Worthen from a single specimen which did not 

 show the anal side. Nevertheless the form is readily recognized, and the validity of the 

 species is now confirmed by a splendid series of eleven specimens occurring in the Browns- 

 port beds associated with Pycnosaccus. The preservation is excellent, leaving little 1 to be de- 

 sired in the way of structural detail except the interbrachial perisome, which we were not 

 fortunate enough to find intact as in the specimens of that genus, although remnants of it are 

 to be seen in some places. As is shown by the figures, the perisome in some cases directly 

 succeeds the broad truncate interbrachial (PL XIV, fig. 2b), and in others is separated from 

 it by plates at the lateral sloping faces connecting with the primibrachs. The apex of the 

 large interbrachial, however, remains truncated to some extent, and I am inclined to think 

 that some part of the distal edge of the plate was always in contact with perisome. The 

 number of primibrachs and secundibrachs, two of each, holds good almost without exception 

 in all the specimens of this species ; which is interesting as contrasted with their great insta- 

 bility in the Swedish species. The bead-like appearance of the stem for almost its entire 

 length is very marked ; after the first few proximals the alternation of the columnals becomes 

 inconspicuous and rather irregular. In the complete specimen shown by figure 3, the stem 

 is preserved to the very end, and there is no sign of any structure for attachment ; it ends in a 

 fine point, capable of twisting about other objects. 



Types. Author's collection. 



Horizon and locality. Silurian, Niagaran Group, Brownsport limestone ; Decaturville, 

 Tennessee. A closely related form occurs in the Laurel limestone at St. Paul, Indiana. 



Hormocrinus anglicus n. sp. 

 Plate XIV, figs. 6, 7 



Specimens larger than in H. tennesseensisj too much flattened to admit 

 measurement of contour, but calyx is similarly low and spreading ; much wider 

 than high ; spread from IBB to top of RR, about 1 to 3. Delicate ridges pass 

 from IBB and BB.to RR, thence following median line of rays to the higher 

 brachials. Crown relatively higher than in that species owing to the greater 

 number of IIBr; approximately about 15 mm. high and 16 wide. Surface dis- 

 tinctly ornamented with small pustules, tending to form longitudinal costae on 

 the brachials and also on the column. 



IBB pentagonal in side view. Anal and first iBr rather small, followed by 

 a second range of plates adjoining IBr, probably not meeting at the middle. 



