PLATE 58. 

 Melonechinus keeping! sp. nov. Page 384. 



Fig. 1. Lower Carboniferous Limestone, Gledstone, Gisburn, Yorkshire, England. Museum of Practical Geology, Lon- 

 don, 6,583, holotype. Natural size. There are twelve columns of plates in an ambulacra! area near the mid-zone. 

 Just above the letter J are seen the two median columns of occluded plates, which are relatively narrow for the genus 

 and not built up in melon-like ribs (pp.359, 384). There are plates of ambulacrum B in place dorsally which serve to 

 fix the limits of the interambulacrum. The interambularrum has six columns of plates, but columns 1 and 2 drop out 

 dorsally indicating senescence; tubercles and peripodia are well preserved. A highly specialized species. Drawings, 

 Plate 59, figs. 1-3. 



Melonechinus giganteus (Jackson). Page 389. 



Fig. 2. Mississippi Group, Ixiwer Carboniferous, Cumberland Gap, Tennessee. U. S. Nat. Mus. Coll., 39,909. Natu- 

 ral size. (This is the holotype of Melonites granulatiis Troost, which with present evidence is not distinguishable 

 from giganteus, and is here considered a synonym, p. 392). There are twelve columns of plates in an ambulacral 

 area; the interambulacrum is incomplete, so that the number of columns is unknown, but a left adradial and five 

 median columns are in place (p. 392). Drawing, Plate 59, fig. 4. 



Melonechinus etheridgii (Keeping). Page 385. 



Fig. 3. Lower Carboniferous Limestone, Clitheroe, Lancashire. (In regard to the locality of this specimen see p. 387.) 

 Museum of Practical Geology Coll., London, 6,578, paratype. Natural size. There are six columns of plates in 

 the left half-ambulacrum and also some plates of the right half-ambulacrum. Above the letter J are seen the two 

 median columns of occluded plates which are relatively narrow for the genus and as in M. keepingi are not built up in 

 melon-like ribs as they are in American species of the genus (pp. 359, 386). Six of the probably seven columns of 

 plates are in place in the adjacent interambulacral area. Spines, tubercles, and peripodia are preserved in parts. 

 Drawing, Plate 59, fig. 5. 



Fig. 4. Same horizon, Clitheroe, Lancashire. (In regard to the locality of this specimen see p. 387.) Museum of 

 Practical Geology Coll., 6,577, holotype. Natural size. Part of Keeping's original slab, composed of more or 

 less dissociated ambulacral areas and interambulacral plates. Drawing, Plate 59, fig. 6. 



Melonechinus vanderbilti sp. nov. Page 388. 



Fig. 5. Ixiwer Carboniferous. Locality unknown, but probably from Tennessee. Vanderbilt University Coll., 220, 

 holotype. Natural size. The specimen is a siliceous internal mold, or in part a siliceous pseudomorph of the plates. 

 There are twelve columns of plates in an ambulacral area at the mid-zone and nine columns of plates in each of the 

 five interambulacral areas. The numbers in white indicate the points of introduction of the several interambulacral 

 columns. Drawings, Plate 61, figs. 1-4. 



Figs. 1, 3, and 4 from photographs taken by J. W. Tutcher; fig. 2 by H. W. Tupper; fig. 5 by F. A. Saunderson. 





