312 New Species of Crinoidea from the 



plates are very massive, the internal cavity being less than 

 half the whole diameter. 



This species differs remarkably from any known species 

 in the sub-carboniferous rocks of this country. Its nearest 

 relations are with Cyathocrinus pentnlobiis, (Iowa Geol. 

 Rep.pl. 25, fig. 5,)= Grap/iiocrinus quatuor-decim-hrachialis 

 of Lyon, (Kentucky Geol. Rep. pi. 1, fig. 2;) from which it 

 differs in the greater disproportion in the size of the plates, 

 which are not produced in nodes or tubercles. 



Geological formation and locality. Keokuk limestone, 

 Keokuk, Iowa. Collection of C. A. White. 



Scaphiocrinus doris (n. s.). Body narrowly calyculate, 

 base truncate, the sides gently expanding to the top of the 

 first radials. Basal plates small, about as high as wide, 

 obtusely angular above. Sub-radials proportionally large, 

 the height one fourth greater than the greatest width, three 

 hexagonal and two heptagonal. First radial plates much 

 smaller than the sub-radials, wider than high. Second 

 radials elongate, pentagonal, obtusely angular above, and 

 strongly contracted on the sides just above the middle. 

 Anal plates large ; the first pentangular, resting upon two 

 sub-radials, and partially supporting the right radial plate ; 

 the second anal rests upon the truncated top of the sub- 

 radial plate ; the form of this and the succeeding one not 

 determined. 



Arms double from their origin ; those of the anterior 

 ray bifurcating on the tenth plate, those of the antero- 

 lateral rays bifurcating on the eighth or tenth plate, and 

 those of the other rays bifurcating at about the same dis- 

 tance ; the plates below a little longer than wide, shorter 

 above the first bifurcation, contracted in the middle, and 

 thickened at the extremities. Proboscis large and strong, 

 extending at least two and a half inches above the first 

 radial plates. 



Surface of sub-radial plates each marked by two strong 



