MELONECHINUS. 375 



of plates composed of wide occluded, narrow demi-, and three somewhat irregular columns of 

 isolated plates in each half-area. The occluded plates medially are elevated in high, steeply 

 rounded, melon-like ridges. Pore-pairs are in deep sunken valleys on either side and are situated 

 in the outer portion of each ambulacra! plate. 



The interambulacra are slightly wider than the ambulacra, and are arched up in high melon- 

 like ridges, the outer faces on a gentle curve, laterally dipping suddenly down to the adradial 

 sutures. Each of the three interambulacral areas preserved has eight columns of plates at the 

 mid-zone. Dorsally, the apical disc is partially preserved (Plate 44, fig. 4); it measures 15.5 

 mm. in diameter, which is about 13 % of the diameter of the test. Ocular D is in place, reaches 

 the periproct, and ventrally covers the ambulacrum and laterally the interambulacra in part 

 on either side. Spaces exist between the genitals for oculars B and J. Four genitals are in 

 place; they are high and wide as usual, each having three genital pores. 



This species is close to multiporus, having the same number of columns of ambulacral and 

 interambulacral plates as that species has. It differs in the high, steeply rounded melon-like 

 ridges and deeply sunken poriferous areas (compare Plate 55, figs. 1-3; Plate 60, figs. 1, 2). 



Lower Carboniferous, detailed horizon and locality unknown, but doubtless, from the 

 lithological character, from Kentucky or Tennessee. Holotype in Vanderbilt University Col- 

 lection, Nashville, Tennessee, 221. 



*Melonechinus multiporus (Norwood and Owen). 



Text-figs. 13, p. 54; 20, p. 59; 25, p. 70; 48, p. SO; 163, p. 149; 237, p. 231; 245, 246, p. 3S2; Plate 54, fig. 5; 

 Plate 55, figs. 1-3; Plate 56, figs. 2-13; Plate 57, figs. 1-3; Plate 60, figs. 1,2; Plate 72, fig. 12. 



Mclonites multipora Norwood and Owen, 1S46, p. 225, text-figs. 1-3; Engelmann, 1847, p, 124; Desor, 

 1858, p. 159; Roemer, 1855, p. 312, Plate 12, figs. l-6c; Meek and Worthen, 1S66, p. 227, text-fig. 

 21; p. 228, text-figs. 21, 22; p. 248, text-fig. 27; A. Agassiz, 1874, pp. 647, 648, text-figs. 1, 2, 5, 6; 

 Quenstedt, 1875, p. 380, Plate 75, figs. 44-50; Keyes, 1894, p. 125, Plate 16, figs, la, lb; Plate 17, 

 figs, la-lc; (pars) Keyes, 1S95, p. 181, Plate 19, figs, la, lb; Plate 20, figs, la-lc; Troost in Wood, 

 1909, p. 107. 



Palarchinus multipora d'Orbigny, 1850, p. 154. 



Mcioncchlnus multiporus Meek and Worthen, 1860, p. 390; Lambert and Thiery, 1910, p. 120. 



Melonites irregularis Hambach, 1884, p. 549, Plate C, fig. 2; Jackson, 1896, p. 240; Klem, 1904, p. 41. 



Melonites multiiMrus Miller, 1889, p. 361, text-figs. 364-366; Jackson and Jaggar, 1896, pp. 135-170, text- 

 fig. 1, p. 164, Plate 2, figs. 1-7; Plate 3, figs. 8-17; Plate 4, fig. 18; Plate 5, fig. 20; Jackson, 1896, 

 p. 191, text-fig. 1, p. 240; 1899, p. 131; (pars) Klem, 1904, pp. 2-6, 42, Plate 1, figs, la-lc; Plate 2, 

 figs. 4a-4d; Plate 3, figs. 6a-6d, 7a-7e; Plate 4, figs. 8a-8f, 9d; Plate 5? figs. 9a, 9b, 10a, 10b, 11, 

 12d; Plate 6, figs. 10c, 12a-12c, 13a-13c. 



Melonechinus irregularis Lambert and Thiery, 1910, p. 121. 



This species is known from very extensive and usually well preserved material from St. 

 Louis, Missouri. I have enjoyed the privilege of studying material in many museums, includ- 



