510 PALEONTOLOGY OF ILLINOIS. 



ties. Our species likewise shows no traces of the furrows on the cast 

 of the upper side of the head, so strongly marked ou I. Barriensis. 



It is still more widely removed from I. insignis of Hall ; and we kuow 

 of no other described species, having the head so nearly elliptical iu 

 outliue, as seen from above, excepting possibly I. Salteri of Barrande, 

 which, however, differs widely in other characters, belonging, as it does, 

 to the small eyed section of the group. 



Position and locality : Grafton, Illinois ; from the Niagara division of 

 the Upper Silurian. 



Gexus SPLEEREXOCHUS, Beyrich. 



Sph^rexochus Bomin&eri, Hall. 



PI. 24, Fig. 4. 



Sphwrexochus Kmningcri, Hall, 1862. Geol. Rep. of Wis., p. 434, and 20th Regents' Report, p. 425. 



PI. 21, figs. 4-7. 



Position and locality : Joliet, Illinois ; Niagara Group. 



DEVONIAN SPECIES. 



Genus CALCEOCRIXUS, Hall. 



Calceocrinus Barrisi, Worthen. 



Body above the medium size and composed of thick massive plates. 



Lower dorsal plate triangular and about three times as wide as high. 



- — ^f^S) Upper dorsal plate less than half the size of the lower, 



WKjf and triangular in outline. Dorsolateral pieces pre- 



Slp senting an irregular pentagonal outline, with abruptly 



■<^>^ roundiug lateral sides, and projecting upper angles. 



Calceocnnvs JBamsi. 



view of the body. Arms and column unknown. 



This species may be readily distinguished from any other known to 

 us by its thick massive plates and robust appearance. We are indebted 

 to the Bev. Mr. Barris, of Davenport, Iowa, for the only specimen we 

 have seen, to whom we dedicate the species. 



Position and locality : Davenport, Iowa; in beds of Devonian age. 



