1879.] NATURAL SCIENCES OF PHILADELPHIA. 265 



ond radials wedgeform, shorter, but as wide as the first. The 

 third radials support two arms which bifurcate once. The arms 

 are extremely short, composed of very few joints, tapering rapidly 

 upward, infolding, inclined obliquely from left to right, and when 

 closed they fit so neatly one into the other, that it appears as if 

 they formed together with the calyx a continuous body. Arm 

 joints single, slightly cuneate. Inter radials none. Anals one, sub- 

 quadrangular, resting upon the larger basal. Column round, com- 

 posed of thin joints near the body, increasing in length so rapidly 

 towards its base, that in four inches the joints attain a length of 

 half an inch. Central perforation of medium size. 



L. Schultze, in his Monograph der Echinod. Eifl. Kalk., p. 40, 

 pronounces Mespilocrinus a synoivyra of Lecanocrinus. In this 

 he is evidentby mistaken. Lecanocrinus has arms like Ichthyo- 

 crinus, while those of Mespilocrinus, in place of being straight, 

 are turned to the right, and the radial and arm plates are conse- 

 quently wedgeform instead of rectangular. Schultze's Lecano- 

 crinus Rcemeri, on which he based the above conclusion, is a most 

 interesting species to show the relations between the two genera. 

 It occurs in the Devonian and zoologically occupies an intermedi- 

 ate position between the Silurian form Lecanocrinus and Mespi- 

 locrinus of the Subcarboniferous. L. Bcemeri not only has very 

 short arms, but they fold up almost as in Mespilocrinus, yet they 

 have rectangular joints and are not deflected. The species has 

 also the unsymmetrieal arrangement of the anal area, but the odd 

 plate is here exceedingly small, and has, when combined with the 

 large one, exactly form and proportions of the single anal plate 

 in Mespilocrinus, thus approaching and foreshadowing the bilateral 

 form which succeeded in the Subcarboniferous. 



Mespilocrinus seems to be strictly a subcarboniferous genus, 

 and only four species are known : 



1853 Mespilocrinus Forbesianus De Koninck andLehon. Recherch . Crin. Belg. , 

 p. 112, pi. ii., figs. 1 a-c. Mountain liuiest. England and Belgium. 



1853. Mespilocrinus granifer De Koninck and Lehon. Recherch. Crinoid, Belg., 

 p. 114, pi. ii , figs. 6 a-c. Mountain limest. Vise, Belgium. 



1859. Mespilocrinus Konincki Hall. Supplem. Geol. Rep. Iowa, p. 69. Burlingt. 

 limest. Burlington, Iowa. 



1861. Mespilocrinus scitulus Hall. Prelim. Not. New Pal. Crinoids, p. 9. Bur- 

 lingt. limest. Burlington, Iowa. 



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