33 



Cijathocrinidce. If this was the form he had in hand when his des- 

 cription was written, it can hardly hold the species in the absence 

 of any figure or diagram to show the error in its diagnosis. 



Position and locality : Upper beds of Keokuk limestone, Hamil- 

 ton, 111. 



No. 174 of Mr. L. A. Cox's collection. 



CYATHOCEINUS ? MARSHALLENSIS. N. SP. 



The crinoid for which the above specific name is proposed, I have 

 been unable to assign with certainty to any known genus. 

 . Its general aspect is that of a Poterlocrinus, but it differs so essen- 

 tially from that in its diagnosis, that I have placed it among the 

 Cyathocrinidce, where it seems to belong. 



Diagnosis : Body mamillate, length and breadth about equal, and 

 truncated at the base where it joins the column. Basal plates small, 

 longest on the anterior side, angular above, and forming by them- 

 selves a shallow pentagonal cup. Subradials about as high as wide, 

 four of them of equal size and hexagonal, the fifth on the anterior 

 side nearly twice as large as the others and heptagonal. The radials 

 on four of the rays are about the same size as the smallest subra- 

 dials, pentagonal in form, their lower angles fitting into depressions 

 between the subradials, constricted from the lower lateral angles 

 upward, so that the upper margins, which support the brachials, are 

 only about half as wide as the greatest width below. 



Brachials three on these four rays, narrower than the radials, two of 

 them quadrangular, and the third angular above, supporting the first 

 divisions of the arms. The lateral spaces between the brachials, and 

 extending below to the middle of the radials, appears to have been 

 filled by a calcareous integument, or with minute plates that are too 

 small to present definite forms under an ordinary glass. 



On the anterior side of the specimen, the large anterior subradial 

 is succeeded by a quadrangular radial resting directly upon its trun- 

 cated upper margin, and this is succeeded by two or more 

 quadrangular brachials, beyond which its structure cannot be 

 made out. 



The arms after the first bifurcation on the third brachial, divide 

 again on the sixth or seventh plate, and some of the branches once 

 or twice more, higher up. They are composed of rather long, round- 

 ed quadrangular joints, decreasing gradually in size to their extrem- 

 ities. Anal plates unknown. 



Column round, very strong at the base of the calyx, decreasing 

 about one-half in diameter a half inch below, and composed of rather 

 thin, even joints. 



Position and locality : Kinderhook group, Marshalltown, Iowa. 



The author's collection. 



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