FOSSILS OF THE KEOKUK GROUP. 485 



Locality and position. Henderson county, near Biggs ville, Illinois ; 

 from the Keokuk group of the Lower Carboniferous. 



BARYCRESTJS GEOMETRICUS, M. and W. 



PL 12, Fig. 3. 



(See Tol. HI, page 518. of these Reports, for description of an undetermined specie* of Cyathocri- 



n '/f .' also same, PI. 20, Fig. 5.) 



Locality and position Keokuk division of Lower Carboniferous, near 

 Warsaw. Illinois. 



BARYCKIXUS HOYEYI, var. HERCULEUS, M. and W. 



PI. 13. Fig 2. 



Barycrinus Hoveyi, var. Hernileus. MEEK and WOKTHKN. Proceed. A.cad. Xat. Sci., Phila., 1868, 

 p. 341. 



Amongst other Criuoids from Crawfordsville, Indiana, we have be- 

 fore us several very large, fine specimens, agreeing well with Professor 

 HALL'S description of his Cyathocrinus Hoveyi (Bost. Jour. Xat. Hist., 

 Vol. vii, p. -93), excepting in some important points in the structure of 

 the arms. We suspect that these specimens are specifically distinct, 

 but as neither any measurement, nor figures of the C. Hoveyi, have yet 

 been published, we cannot feel quite sure of this, and therefore place 

 them, provisionally, as a variety of the species Hoveyi, under the name 

 Hercnleus. which we propose to retain for the species, if the differences 

 to be noted are found to be constant and of specific value. 



The differences to which we allude are the following : In C. Hoveyi 

 the arms of the autero-lateral rays are said to " have the anterior divis- 

 ion twice bifurcating, above which the divisions give off brauchlets, 

 and the same feature marks the entire length of the lateral arm of the 

 autero-lateral ray, which is smaller than the other." In the specimens 

 before us the anterior lateral rays have each the posterior division bifur- 

 cating once near the base, while the anterior division is simple and larger, 

 instead of smaller, than the other. Again, the Hoveyi is said to have, 

 "in the postero-lateral arms, ;the lateral division of the rays bifurcating 

 on the fourth piece, above which branchlets are thrown off, as in the 

 others." In the specimens before us, however, both arms of the poste- 

 rior rays are, like those of the anterior ray, and one of each lateral (or 

 anterior lateral) rays, simple from their origin on the third radials, very 

 long, stout, and give off along their inner lateral margin stout, sim- 

 ple armlets, alternately at regular intervals. As we have seen several 

 specimens all agreeing in these characters, we are inclined to think this 

 may be a specific difference. 



