PLATE 60. 

 Melonechinus multiporus (Norwood and Owen). 



Page 375. 



Fig. 1. St. Louis Group, Lower Carboniferous, St. Louis, Missouri. F. Springer Coll., 8,023 (from G. Hambach Coll.). 

 Natural size. A quite typical adult specimen; melon-like ribs are rounded, moderately elevated; there are eight 

 columns of plates in each interambulacral area; interambulacral plates are rhombic dorsally; ocular and genital 

 plates are all in place. Genital G has three or perhaps four pores, all other genitals have three pores each. The 

 apical disc measures proportionately 16% of the diameter of the test (pp. 376, 379, 384). 



Fig. 2. Same horizon and locality. F. Springer Coll., 8,108 (from G. Hambach Coll., K 8, the original of Miss Klein's, 

 1904, Plate 4, figs. 8a-8d). Natural size. Similar specimen to the above, but with nine columns of plates in each 

 interambulacral area. Oculars are all insert. Genital E has three pores, genitals A and C apparently have four 

 pores each, genital I is doubtful, and genital C! has only two pores, a very unusual number. No pores seem to have 

 been obliterated in this plate. The diameter of the apical disc measures proportionately about 16% of the diameter 

 of the test (pp. 379, 384). 



Melonechinus giganteus (Jackson). 



Page 389. 



Fig. 3. Lower Carboniferous, Bowling Green, Kentucky. Mus. Comp. Zool. Coll., 2,989, holotype. Natural size. Ven- 

 tral view. The specimen is a siliceous pseudomorph in fine condition of preservation and represents probably the 

 largest known Palaeozoic echinoid. Melon-like ribs are strongly and sharply elevated. There are twelve columns 

 of plates at the mid-zone in the ambulacral areas and eleven columns of plates above the mid-zone in each interambu- 

 lacral area. The introduction of the columns of interambulacral plates can be plainly followed in several inter- 

 ambulacral areas, and is especially clear in area A. As seen imperfectly on the dorsal side of this specimen the apical 

 disc measures about 15-16% of the diameter of the test. Drawings, Plate 59, figs. 12-15. 



Figs. 1, 2, photographs by F. A. Saunderson; fig. 3 by C. H. Currier. 



