PLATE 24. 



Hyattechinus pentagonus sp. qov. Page 295. 



Figs. 1-4. Waverly Group, Lower Carboniferous, Meadville, Pennsylvania. 



Fig. 1. Alleghany College Coll. Holotype. Natural size. External mold of the dorsal side. The test is strongly pentag- 

 onal in outline; ambulacra are narrow, interambulacra broad, each with 14 columns of plates in each area, geni- 

 tal and ocular plates in place. The apical disc is small, being proportionately about 16% of the diameter of the 

 test. Drawings, Plate 25, figs. 3, 4. 



Figs. 2, 3. Similar external molds of the dorsal side of two other specimens of the same species and on the same slab. Para- 

 types. 



Fig. 4. Mus. Comp. Zool. Coll., 3,107 (from R. T. J. Coll.). Paratype. Natural size. External mold of the ventral 

 side. Ambulacra broad, petaloid. Primordial interambulacral plates in the basicoronal row; additional columns 

 of plates come in with a very accelerated development. Drawing, Plate 25, fig. 1. 



Hyattechinus beecheri sp. nov. Pane 2!i7. 



Figs. 5-S. Waverly Group, Lower Carboniferous, Warren, Pennsylvania. Obtained by the late Professor C. E. Beecher 

 from the late Dr. Randall, who collected it; now in Yale Univ. Mus. Coll., 323. Holotype. Natural size. Bilat- 

 erally symmetrical through an ambulacrum and opposite interambulacrum, which I consider as the axis III, 5, a 

 unique character in regular Echini (p. 32). The specimen is an internal mold representing an impress of the inner 

 side of the plates, but so nearly perfect, that it is represented spread out in Plate 26. 



Fig. 5. Ventral view. Natural size. Ambulacra broad, petaloid, ambulacral pores represented by elevated plugs. In 

 addition, each plate vent rally bears a reentrant elongate pit which represents the impression of an elevated spine- 

 like process on the inner face of the plates, seen best in areas III and IN 7 . Primordial interambulacral plates are in 

 the basicoronal row and additional interambulacral columns come in rapidly, the full number being attained at or 

 just above the ambitus. 



Fig. 6. Drawn from a wax cast of the ventral side which therefore represents the internal face of the ventral plates. X 3.7. 

 The pore-pairs exist as pits and the spine-like elevated processes stand up as ridges; from the area indicated by X 

 in Plate 26. (Compare Plate 3, figs. 12, 13; p. 61.) 



Fig. 7. Side view, in profile. Natural size. The test is apparently of the original form and height. 



Fig. 8. Dorsal view. Natural size. Ambulacra narrow, plates low, the impressions of the genital and some periproctal 

 plates are in place. The apical disc is small proportionately to the length of the test . This specimen is shown spread 

 out in Plate 26, and the apical portion is shown in Plate 25, fig. 5. 



Figs. 1-3 photographed by H. W. Tupper; other photographs by F. A. Saunderson; the drawing, fig. 6, by J. Henry 

 Blake. 



