304 



ECHINODERMATA— ECHINOZOA 



PHYLUM IV 



second developmental stage. Lower Carboniferous ; Europe and North 

 America. 



Oligoporiis Meek and Worthen (Fig. 367, m). Four columns of plates in 

 each ambulacral area, consisting of demi-, occluded, and in addition scattered 

 isolated plates ; pore-pairs multiserial. Four to nine columns of plates in each' 



J 



Fig. 432. 



Loticiiechinus scpties Jackson. Lower Carlioniferous ; Boouvillf, Missouri. .1, In llie centre, spread out to 

 show structure and development, dotted lines indicate restorations. IS, Lower lel't-liand tigurc, developing 

 ambulacrum ventrally. C, Lower right-hand tlgure, anibnlacrum near mid-zone. I), Upper right, developing 

 ambulacrum dorsally. E, Upper left, apical disk witli coronal contact. A, Natural size ; other figures tliree 

 times enlarged (after Jackson). 



interambulacral area. This genus differs from Lovenechinus in that it has 

 isolated plates in addition to the four columns of ambulacral plates. Lower 

 Carboniferous ; North America. 



Melonechinus Meek and Worthen {Melonites Norwood and Owen). (Fi 

 ^. d: 367. n: 371. D -, 433). Six to twelve columns of plates in ei 



SfS. 



366, il; 367, n; 371, D ; 433). Six to twelve columns of plates in each 

 ambulacral area, consisting of demi-, occluded and one to four irregular 



