FOSSILS OF THE BUKLDsGTOX GKOUP. 439 



Crinoids. in wbicli oiie would less expect to find such an elongated ven- 

 tral tube, than in this. 



L<-<ility and position Upper division of the Burlington group, at 

 Burlington, Iowa. Lower Carboniferous. Xo. 335 of Mr. WACHSMUTH'S 

 collection. 



SYXBATHOCRISTJS BREYIS, M. and W. 



PL 2, Fig. 6. 

 Synbathocrinus brevis, MEEK and WORTHBX. Proceed. Acad Nat. Sci., Phila., 1869, p. 66. 



BODY small, expanding rather rapidly, with nearly 

 straight sides from the base to the top of the first radial 

 pieces, thence contracting very slightly to the top of the 

 second radials. Form and arrangement of the body pieces 

 very nearly as in the last. Arms comparatively short and 

 tapering rather rapidly at the extremities, angular or sub- 

 carinated along the middle of the dorsal side, the carina 

 being interrupted or obsolete near the sutures between the 

 arm piecs, so as to present, as seen in outline, a subcrenate 

 appearance; arm pieces eighteen to each ami, excepting -the 

 first one. slightly wider than long. Column slender, round, 

 and composed of alternately thinner and thicker pieces near 

 the base, some of these 0.25 inch farther down, however, 

 being as long as wide, all marked with strong radiating 

 stride on their articulating surfaces, and pierced by a small, 

 apparently round, central canal. Surface- finely granular. 



Hight of body to the top of the first radial pieces, 0.15 

 inch; to top of second do., 0.20 inch; breadth, 0.21 inch; 

 length of anus, 1.35 inches. 



This species will be readily distinguished from /&'. Worthtni, S. den- 

 tat us and S. 2)apiUatus, by its much shorter arms, which have scarcely 

 two-thirds as many pieces as in those species. Its body is also rather 

 less spreading, and slightly more inclined to round in to the column 

 below, but not near so much so as in the last described species, from 

 which it also differs in having much shorter arms. 



L<>tlify and position Lower Burlington beds, Burlington, Iowa. 

 Lower Carboniferous. !No. 336 of Mr. WACHSMUTH'S collection. 



