90. CONTRIBUTION TO 



Figures 7 and 8 illustrate a peculiar deformity. A similar specimen is 

 figured by Etheridge and Carpenter on Plate 2, Figs. 8-9 in "The Catalogue of 

 the Blastoidea." 



There are five radial plates, but one is narrow and without an ambulacrum, 

 being imperceptibly grooved. One of the four ambulacral fields (the one on 

 the right of the deformed radial) is broader than the other three, a ridge pass- 

 ing down the middle of it. As this ridge is composed on each lateral face of 

 side plates, we have here in this abnormal ambulacral area two ambulacra with 

 their abutting edges pushed vip into a ridge-like fold. 



The specimens of Pentremites godoni, here figured, are from near Bowl- 

 ing Green, Ky., and are the property of Mr. G. K. Greene. 



PENTREMITES KONINCKANUS, Hall, Rowley. 



Plate 29. Figs. 5, 6, 9, 10, 10a, 11, 13, 14. 



Figs. 9, 10a, 11 are illustrations of a tetraradiate specimen, but with one am- 

 bulacral field broader than the rest and the medial groove occupied by a broad, 

 rounded ridge, composed of a double row of side pieces, the whole forming a 

 double ambulacrum. The abnormality of this specimen diiTers from that of 

 the Pyviformis., Figs. 7 and 8, in the absence of the fifth radial. 



Figures 13 and 14 represent a symmetrical tetraradiate specimen. There 

 are two such in the collection. 



The specimen represented by figures 5 and 6 preserves a part of the mid- 

 ventral pyramid, but more poorly preserved than the same structure in Figures 

 3 and 4. 



All these specimens of Koninckanus are enlarged to two diameters. 



They were collected from the Warsaw group at Lanesville, Ind. So also 

 were all of the figured specimens of P. conoidetis, and are a part of the collec- 

 tion of Mr. G. K. Greene. 



TRICCELOCRINUS WOOD MANX, M. and W., Rowley. 



Plate 29. Figs. 35, 36, 42, 43. 



The figures represent a badly decorticated specimen, restored in plate sur- 

 face by the artist. It is figured here merely to show the base of the triangular 

 column and its minute central perforation. It would be inter.gsting to know if 

 triangular columns occur in the Warsaw beds, where this blastoid is found, 

 and it is probable that all species of this genius have, at least, the bases of 

 their columns triangular. 



Figures 42 and 43 show the portion of column attached to a larger, but 



