FOSSILS OF THE BURLINGTON GEOUP. 415 



eighth or tenth piece above. First, and sometimes also 

 the second arm pieces a little longer than wide, and slightly 

 constricted; other arm pieces generally wider than long 

 and wedge shaped, but not arranged so as to impart a zigzag 

 appearance to the amis. Column small, nearly or quite 

 round, and composed near the base of alternately thin and 

 thick pieces. 



Hight of body to top of first radial pieces, 0.07 inch ; 

 breadth, 0.20 inch; length of arms, about 0.70 inch. 



This little species seems to be nearest like 8. dichotomus. Hall, (Iowa 

 report, p. .V>3), with which it agrees in size and general appearance. It 

 will be readily distinguished, however, by the more frequent bifurcations 

 of its arms, which also differ in being more rounded and composed of 

 proportionally longer pieces, not arranged so as to present a slightly 

 zigzag appearance, as in the species dichotom us. It will also be distin- 

 guished from the last by having two arms to each ray all around, as 

 well as by its concave base. 



Locality and position Upper division of the Burlington group, at 

 Burlington, Iowa. Lower Carboniferous. Xo. 286 of Mr. WACHSMUTH'S 

 collection. 



SCAPHIOCRIXUS MACRODACTYLUS, M. and W. 



PL 2, Fig. 9. 

 Seaphioeriniu macrodactylus, MEEK and WORTHEN. Proceed. Acad. Xat. Sci., Phila., 1869, p. 140. 



BODY obconical, or tapering rather gradually from the 

 top of the first radials to the column. Base about twice 

 as wide at the top as long, truncated below the breadth of 

 the column ; basal pieces a little longer than wide, pen- 

 tagonal in form, with the lateral margins longer than the 

 upper sloping sides. Subradial pieces once and a half to 

 twice the size of the basals, hexagonal in form, except- 

 ing one (or possibly two) on the anal side, which is larger 

 than the others and pentagonal, being truncated above for 

 the reception of an anal piece. First radial pieces wider 

 and a little shorter than the subradials, and all wider than 

 long. Second radials distinctly longer than wide, rounded 



