FOSSILS OF THE BURLINGTON GROUP. 379 



Carboiiiferous, at Burlington, Iowa. No. 14 of Mr. WACHSXUTH'S col- 

 lection. 



BATOCRLNTJS CHRISTYI, Shumard's sp. 



PL 5, Fig. 4. 

 Actinocrinus Christyi, SHUMARD. Geol. Survey of Mo., Part 2, p. 191 ; PL a, Fig. 3. 



BATOCRIXUS VERXEUILIA^US, Shum. sp. 



PI. 4, Figs. 3 and 4. 

 A'-tlniKriniteg verneuilianm, SHUMARD, 1853. Geol. Survey of Mo., Part 2, p. 193; PL a, Fig. 1. 



(Specimens of this species, showing stem, proboscis and arms : Burlington limestone, Sagetown , 

 Illinois, and Burlington, Iowa.) 



GEXUS DOKYCRLSTrS, Rcemer. 



In the second volume of the Reports of the Geological Survey of 

 Illinois we distinctly recognized the Dorycrinus group as forming a well 

 denned genus, clearly separated from Actinocrinus (as properly restrict- 

 ed), to which genus they have generally been referred ; but owing to 

 the fact that at that time we had never seen either a specirnan or a figure 

 of an Amiriioracrinus showing the arms, body and parts connected with 

 the opening of the vault, all preserved together, we were under a mis- 

 apprehension in regard to the true characters of that group, and conse- 

 quently placed Dorycrinm as a synonym under it. Recently, however, 

 we have been so fortunate as to see in Mr. WACHSMUTH'S extensive col- 

 lection beautiful specimens of both types, in a remarkably fine state of 

 preservation, and from these we are satisfied that a systematic classifi- 

 cation of the Crinoidea requires these two groups to be separated as dis- 

 tinct genera. 



In the first place, it may be proper to remark that in both of these 

 groups the structure of the body, so far as regards the number and 

 arrangement of the pieces below the arm-bases, is almost exactly the 

 same as in Actinocrinus.* The structure of the parts above, however, 

 is very different. For instance, in Dorycrinus the opening of the vault 

 is never at the end of a more or less prolonged tube, or so-called pro- 

 boscis, nor even in the slightest degree proboscidiform, but is merely a 

 simple aperture penetrating a somewhat thickened protuberance, and 

 nearly always situated and opening laterally. The vault in this group 

 is generally provided with a more or less prominent spine over each 



* Dorycrinu*, however, differs from Actinocrinus, in having the second radial pieces nearly always 

 short and quadrangular, instead of hexagonal. 



