PLATE 67. 



Perischodomus harteiana (Baily). Page 408. 



Figs. 1-3. Same specimen us photographs, Plate 0.5, figs. 1 and 2. Holotype. 



Fig. 1. From near the mid-rone. Drawn from the original mold; therefore the lettering is reversed. X about 3. 

 Three columns of ambulacral plates in a half-area. 



Fig. 2. Interambulaerum drawn from a plaster cast of the original mold. X 1.1. Five columns of plates near the mid- 

 zone; columns 5, 4, and 3 drop out dorsally. 



Fig. 3. Drawn from a plaster cast of the original mold. X 1.4. Oculars insert, four genitals with three, five, or six pores 

 each. No pores visible in genital E. Interambulacrum in contact with the oculars laterally. 



Proterocidaris giganteus Koninck. Page 410. 



Figs. 4-7. Lower Carboniferous, Dinant, Belgium. Drawn from Fraipont's, 1904, photographic figures of what he calls 



Oligoporus soreili sp. nov., here considered a synonym. 



Fig. 4. Segment of interambulacrum from mid-zone, seen from the exterior, adapted from Fraipont, 1904, Plate 5, fig. 1. 

 X 0.9. There are 13 columns of interambulacral plates, the 13th originates on the left; an adjacent adradial plate, 

 X, has six instead of five sides as is usual. Small primary with secondary tubercles. 



Fig. 5. Segment of an interambulacrum and ambulacrum, a little above the mid-zone, adapted from Fraipont's, 1904, 

 Plate 5, fig. 2 (orientation reversed from his figure). X 0.9. Internal view. Four columns of plates in an ambula- 

 cral area (in B the plates are mechanically separated in the median line); pore-pairs in the middle of half-areas. 

 Twelve columns of interambulacral plates, the twelfth originating on the left (right as seen from exterior). 



Fig. 6. Same specimen as photograph, Plate 65, fig. 3. X 0.9. From interambulacrum I to show imbrication as seen from 

 interior; plates bevel adorally and toward the center and over plates of column 9. (Compare Plate 19, fig. 1.) 



Fig. 7. The same specimen. Interambulacral plates showing small primary and secondary spines. X 1.9. 



Lepidesthes wortheni Jackson. Page 416. 



Figs. 8, 10, 11, 13, 14. Keokuk Group, Lower Carboniferous, Crawfordsville, Indiana. 



Fig. 8. Same specimen as photograph, Plate 66, fig. 1. X 1.8. In each ambulacral area there arc eight columns of 

 regular hexagonal plates at the mid-zone; pore-pairs in the upper part of each plate nearest the next adjacent inter- 

 ambulacrum; occluded columns are strongly defined as the pore-pairs are in outer sides of contiguous plates. Inter- 

 ambulacra with three columns of plates at mid-zone. In area A there are three plates in the lowest row seen, in the 

 next row four plates; the fourth column is represented by only four plates, above which there are three columns only. 

 Beveling seen clearly in area A where plates are wanting; secondary tubercles only. 



Fig. 9. Same specimen as photograph, Plate 66, fig. 3 (after Jackson, 1896, Plate 9, fig. 53). Holotype. X 1.8. Four 

 columns of interambulacral plates are seen ventrally in area C and imperfectly in area A, above which there are 

 three columns only. Ambulacral plates are more rhombic at the mid-zone than in figs. 8 and 10. 



Fig. 10. Same specimen as photograph, Plate 66, fig. 2. Ambulacral detail. X 3.6. Ambulacral plates rhombic in form. 

 Pore-pairs in peripodia in the upper left part of each plate in the left half-area and in the upper right part of each 

 plate in the right half-area. Tubercles are similar to those of the interambulacrum. 



Fig. 11. Section at the ambitus to show the beveling of plates, ambulacral plates are shaded. X 1.8. 



Fig. 12. Portion of lantern from reverse side of same specimen as photograph, Plate 66, fig. 3. Holotype. X 2.5. Left 

 and right half-pyramids, foramen magnum shallow; the left epiphysis in place, but the right epiphysis is wanting. 



Fig. 13. Yale Mus. Coll., 319. Spines. X 3. 



Fig. 14. The same specimen, spine enlarged. X 14. Acicular, swollen at the base, with fine vertical striae. 



Lepidesthes laevis Trautschold. Page 418. 



Fig. 15. Lower Carboniferous, Moscow, Russia. Museum fur Naturkunde Coll., Berlin. X 2.4. Seen from the exterior, 

 showing four of the ambulacral and two interambulacral columns. Pore-pairs are in the upper part of plates. 

 Interambulacral plates rounded, imbricating dorsally and laterally; a few tubercles are in place. 



Fig. 16. Same specimen seen from the interior. X 2.4. Pore-pairs are in the lower part of plates, interambulacral plates 

 hexagonal, not rounded as on the exterior. (Compare text-figs. 32-34, p. 75.) 



Figs 17, 18. Lower Carboniferous, Miatschkowa, Province of Moscow, Russia (after Trautschold, 1879, p. 8; the orienta- 

 tion reversed from Trautschold's). Cotypes. Enlarged from Trautschold's original figures. X 1.7. 



Fig. 17. Three of the ambulacral with four interambulacral columns. Interambulacral plates rounded, imbricating. 

 Fig. 18. Specimen with ambulacral plates on each side of the interambulacrum; four columns of interambulacral plates. 



Fig. 9 drawn by J. H. Emerton; figs. 1-3, 15, and 16 from my sketches; figs. 4-7 from Fraipont's photographic figures, 

 figs. 17 and IS after Trautschold; figs. 8 and 10-14 from nature by J. Henry Blake. 



