PLATE 54. 



Melonechinus stewartii (Safford). Page 371. 



Fig. 1. Lower Carboniferous, probably St. Louis Group, Middle Tennessee, but the detailed locality is unknown. Plaster 

 cast of the holotype, which is an external mold. Natural size. The holotype is in Vanderbilt Univ. Coll., 223. Eight 

 columns of plates in an ambulacral area at the mid-zone. In each of the interambulacral areas A to G there are 

 seven columns of plates, but in area I there are only six. The apical disc and pcriproctal plates are well preserved. 

 The apical disc measures proportionately about 17% of the diameter of the test. Drawing from the original 

 molds, Plate 53, figs. 6-8, or directly from a wax cast of same, Plate 56, fig. 1. 



Melonechinus obovatus sp. no v. Page 373. 



Figs. 2, 3. Lower Carboniferous, White's Creek, Davidson County, Tennessee. Vanderbilt Univ. Coll. Holotype. Nat- 

 ural size. The specimen is an internal calcite mold, so that the melon-like ribs, which are a feature of the exterior 

 in most species of the genus, are unknown. Ten columns of plates in an ambulacral area at the mid-zone. In the 

 interambulacra there are only three columns of plates in each area at the mid-zone, the fewest known in the genus 

 or family. 



Fig. 2. Side view, showing the peculiar obovate form, with the ambitus above the mid-zone, a very rare character in Echini 



(p. 32). Drawing, Plate 53, fig. 9. 

 Fig. 3. Dorsal view. No melon-like ribs shown, this being an internal mold; oculars and genitals are all in place. The 



apical disc measures proportionately 25 % of the diameter of the test which is relatively very large for the genus (p. 



374). Drawing, Plate 53, fig. 10. 



Melonechinus liratus sp. riov. Page 374. 



Fig. 4. Lower Carboniferous, locality unknown, but doubtless from Tennessee or Kentucky. Vanderbilt Univ. Coll., 221, 

 holotype. Natural size. High, angular, melon-like ribs in ambulacral and interambulacral areas. Ten columns 

 of plates in each ambulacral area and eight columns of plates in each interambulacral area. Drawing, Plate 53, 

 fig. 11. 



Melonechinus multiporus (Norwood and Owen). Page 375. 



Fig. 5. St. Louis Group, Lower Carboniferous, St. Louis, Missouri. F. Springer Coll., 8,112 (from G. Hambach Coll., 

 K 12, the original of Miss Klein's, 1904, Plate 5, fig. 12d; Plate 6, figs. 12a-12e). Natural size. Low rounded melon- 

 like ribs. In area A there are nine, but in all other interambulacral areas eight columns of plates (p. 384). The intro- 

 duction of the eighth column is seen adorally in areas C and E. Oculars and genitals are clear. Oculars are insert 

 and are in contact with the interambulacra laterally as seen clearly in area D. Genital A has four genital pores and 

 the other four genitals have three pores each (p. 379). 



