EXPLANATION OF PLATES. 



PLATE 36. PAGE 



PENTREMITES OBESUS, Lyon, Rowley. 115 



FIGS. 1, 2-3 — Side, basal and summit views of a fine specimen. 



PENTREMITES SULCATUS, Rocmer, Rowley. 116 



FIG. 4 — Side view of a specimen showing the visceral cavity through 



a break in the test. 

 FIG. 5 — View of a fragment in which the greatly sunken character of 



the ambulacrum is shown as also the folded, irregular edge of the 



bounding radials. 



PENTREMITES CHEROKEEUS, Troost, Rowley. 116 



FIG. 6 — Side view of a medium specimen to show the character of the 

 ambulacra and the bounding radial and deltoid lips. 



PENTREMITES CHESTERENSIS, Hambach, Rowley. 117 



FIGS. 7-H — Side and summit views of a fine, but imperfect specimen. 

 FIGS. 9, 10-11 — Side, basal and summit views of another specimen. 



PENTREMITES ROBUSTUS, Lyon, Rowley. 118 



FIG. 12 — Side view of a specimen apparently of this species. 



PENTREMITES, Sp. (?) 



119 



FIG. 13 — Side view of a unique specimen of doubtful species. 



PENTREMITES PYRIFORMIS, Say, Rowley. 120 



FIG. 14 — Side view" of an unusually large specimen. 

 FIG. 15 — Side view of a young individual. 



FIG. 16-17 — Side and summit views of a specimen with an extra radial 

 plate. 



PENTREMITES GODONI, De France, Rowley. 121 



FIG. IH — Summit view of an abraded surface, showing double spiracles. 



t 



