CLASS 



ECHINOIDEA 



301 



placed primaries with secondaries, or the latter only. Siluriari to Lower. 

 Carboniferous. 



Koninckocidaris Dollo and Buisseret. Test high, probably spheroidal ; 

 ambulacral plates high, two or three equalling the height of an adambulacral 



Fig. 428. 



A, Lepidmentrus rhenanus (Beyr.). üevonian ; Wipperfürth, Eifel. Gast of the interior of test showing 

 jaws, l/i (after J. Müller). B-D, Lejüdocentrus mülleri Schultze. Devonian ; Gerolstein, Eifel. B, Portion of 

 Amh, enlarged. C, Several lAmb plates, l/i ». D, Two detached lAmb plates, showing oblique edges, i/j. 



plate, pore-pairs uniserial. Seven to eight columns of nearly rhombic plates 

 in an interambulacral area. K. silimca Jackson. Silurian ; North America. 

 K. cotteaui Dollo and Buiss. Lower Carboniferous ; Belgium. 



Lepidocentrus Müller (Fig. 428). Test high, spheroidal, ambulacral areas 

 narrow throughout ; ambulacral plates low, about eight equalling the height 



0«2 4 « 



Fig. 



A, Hyattecliinus pentagonus Jackson. External sandstone moulds. Lower Carboniferous; Meadville, 

 Pennsylvania. Ventral view showing introduction of columns and accelerated development of interanibulacra. 

 B, The same, dorsal view, showing fourteen columns in each interambulacral area and the dropping out 

 of soine columns dorsally. Both figures ^/lo natural size (after Jackson). 



of an adambulacral plate, pore-pairs uniserial. Five to eleven columns of 

 plates in an interambulacral area. Small primary spines and tubercles with 

 secondaries on interambulacral plates. Devonian ; Germany and North 

 America. Lower Carboniferous ; North America. 



Hyattechinus Jackson (Fig. 429). Test depressed to flattened ; through 

 the ambitus circular, pentagonal or clypeastriform. Ambulacral areas broad, 



