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Field Columbian Museum — Geology, Vol. IT. 



it rests, are in the form of a rhomb, with its transverse axis equal 

 to the width of the radial plate. In 5. skiffi the rhomb consists of nine 

 striae, but in 5. hammelli there are more than three times that 

 number. In 5. hammelli moreover the curvature of the rhomb con- 

 forms to the general curvature of the calyx, but in 5. skiffi it is decid- 

 edly convex transversely and moderately so longitudinally (PI. 

 LXXXIV, Fig. 16). 



The type specimen (Mus. No. P 8479) consists of a natural cast and 

 more than half the accompanying mold, both in an excellent state of 

 preservation. Several other individuals of this species are in the 

 collections. 



The specific name is proposed in honor of Mr. Frederick J. V. 

 Skiff, Director of the Museum. 



Locality: Niagaran limestone of the spoil heaps of the Chicago 

 Drainage Canal near Lemont, Illinois. 



Family ZOPHOCRINID^E. 



ZOPHOCRINUS S. A. Miller. 



Two new species belonging to this genus were collected by the writer 

 and are here described. This genus differs from all other crinoids in 

 that the calyx contains but four radial plates ; the quadrangular one 

 is somewhat larger than the others and is probably made up of the 

 right and left posterior radials fused, as the tetramerism affects the 

 dorsal cup only; the dome and arms are pentameral. 



Br&i £& u ova \mJ 



Fig. 5. Outline of the (i) Posterior and (2) Ventral Views of the Genotype and (3) Diagram of 

 Zophocrinus. (After Bather.; 



The plates are as follows: Basals three, two equal, one larger; 

 radials four, three equal, one larger. The ventral disc is composed 

 of five orals, the posterior oral is the largest and the two anterior orals 



