PLATE II. 



Pextremites Godoni, Defrance, sp., p. 157. 

 Figs. 1-7. A series of outline figures to show the variations in the form of the calyx of 



this species. Subcarboniferous, North America. All natural size .... 15 



Pentremites Godoni, var. major, E. If ('., p. 160. 



Pig. 1. Radial view of the largest variety of P. Godoni, Defrance, sp. Subcarboniferous 



Tennessee. Natural size 159 



Pextremites Godoni, var. ixorealis, Schlotheim, var., p. 160, 

 Fig. 3. Radial new of the form which appears to represent the species proper. Subcar- 



bonifcrous, Alabama. Natural size 159 



Pextremites Godom, var. ajbbeeviatus, Hambach, var., p. 160. 

 Fig. 4. Radial view of the form termed Pentremites abbreviatus by Hambach. Subcarboni- 



ferous, Illinois. Coll. P. H. Carpenter. Natural size 159 



Pextremites Godoxi, Defrance, sp., p. 157. 

 Fig. 8. Summit view of a tetraradiate specimen with one radial aborted and a median ridge 



on the ambulacrum of another. Subcarboniferous, Alabama. Coll. Wachsmuth. 



xli II 



Fig. 9. A radial view of the same specimen, showing the abnormal ambulacrum. x 1 .', 10 



Fig. 10. Summit view of a distorted tetraradiate specimen, with one ambulacrum aborted. 



Subcarboniferous, Alabama. Cull. Wachsmttth. xH 10 



Fig. 11. Side view of the abnormal radial of this specimen. The sutures at its upper end 



arc rather too distinct. xH 1<) 



Fig. 12. Ambulacrum of another specimen with its food-groove replaced by a ridge as in 



tigs. 8 and 9. Subcarboniferous, Alabama. Coll. Waehsmuth. x 24 . . . in 



Fig. 13. Cross-section of the distal end of an ambulacrum, just above the point at which 



the inward extensions of the radials meet one another beneath the hydrospires. 



Subcarboniferous, Alabama. Coll. P. H. Carpenter. x 1 94 



Pentremites elongatos, Shumard, p. 161. 



Fig. 1 1. Radial view of a I'obust variety. Subcarboniferous, Iowa. Natural size ... 15 

 Fig. 15. Radial view of an elongated and slender variety. Subcarboniferous, Iowa. 



Natural size 15 



Pextremites conoideus, Hall, p. 162. 

 Figs. 16-23. A series of outline figures to show the variations in the form of the calyx. 



Subcarboniferous, North America. Figs. 16-18 represent the species proper. 



Natural size 163 



Pextremites coxoideus, var. Koxixckaxus, Hall, var., p. 162. 



Figs. 19-23. Radial views of the young stages of P. conoideus, showing the variation in 



form according to age. Subcarboniferous, Illinois. Natural size .... 163 



