FOSSILS OF THE BURLINdTOX GROUP. 347 



nodes or short spines, passing gradually into a rather large 

 suhcentral proboscis. 



Surface of all the body plates rather distinctly convex, 

 but not properly tumid, and showing but the faintest traces 

 of an effort to form, on some of the smaller pieces, an ob- 

 scure radiating ridge near each side. In most cases, how- 

 ever, these are entirely obsolete, and the plate seems to be 

 inerelv evenly convex. 



* . 



Hig-ht of body to arm bases, 1.20 inch ; breadth of same 

 at arm bases, 1.40 inch ; hight of vault, about 0.80 inch. 



In the structure of its body, as well as iu its arm formula, this species 

 agrees with Actinocrinm dads, of Hall. It differs, however, greatly in 

 form, as well as iu the surface characters of its body plates, being 

 rather elongate obconical below the arms, instead of " very broadly 

 subturbiuated, and spreading more rapidly above the third radial 

 plates ;" while its body plates are merely convex, instead of being 

 u elevated into strong angular nodes, some sometimes marked by low 

 ridges on the lower part," and by " strong angular ridges " on the upper 

 part. 



Its elevated conical vault, passing gradually into the nearly central 

 proboscis, and narrow obconic body below the arms, give it a peculiar 

 fusiform outline. In the nature of its vault it resembles quite nearly 

 A. << status, of Hall, from which, however, it differs widely in other 

 respects. 



Locality and position Lower beds, Burlington group of Lower Car- 

 boniferous, Burlington, Iowa. Mr. WACHSMUTH'S collection. 



GEXUS STKOTOCKIXUS, M. and W. 1866.* 



(Proceed. Acad. Nat. Sci., Phila.. Id69, p 158.) 



Extending the genus Strotocrinus so as to include, as already sug- 

 gested, the Act. ventricosus group as a subgenus. we will have, first, the 

 typical urn-shaped species, such as $.2)enimbrosus and S. Uratus. with 

 the structure of Actiitocrinites up to the divisions of the rays, but with 

 the body comparatively long and narrow below, and the secondary and 

 other succeeding supplementary radials, brachial and intermediate 

 pieces, connected laterally all around, and spreading out horizontally 

 far beyond the limits of the body, so as to form, with the flat or much 



* Second Vol. niinois Report, p. 188. 1866. 



