I'l.ATK 53. 



Melonechinus indianensis (Miller and Gurlcy). Page 309. 



Figs. 1-4. Same specimen as photograph, Plate 51, fig. 7. Holotype. 



Fig. 1. Dorsal [tortiou spread out. X 3.4. In ambulacrum F there are four columns of plates in a half-area as far ven- 

 t rally ;LS it is shown and the number decreases passing dorsally to the apical disc. Interambulacral columns 1 and 2 

 drop (iut dorsally, indicating aenesoeooe, and some additional columns drop out as column 6 in area G and column 4 

 in area C. Oculars arc all insert and adorally cover the ambulacra and laterally the interambulacra in part on either 

 side. Three genital pores in one plate, and in the other genital plates the pores are partly or wholly obliterated by the 

 process of silicification. 



Fig. 2. Ventral part of the left half of ambulacrum J. X 3.4. Ventrally the plates are all demi- and occluded; higher 

 up isolated plates appear, then three columns, and at the top of the figure there are four columns in the half-area, 

 the species character. 



Fig. 3. Ambulacrum J at the mid-zone. X 3.4. Four columns of plates in a half-area; pore-pairs are in peripodia, tub- 

 ercles on the interambulacral plates. (Compare figs. 1-3 with text-fig. 237, p. 231.) 



Fig. 4. Interambulacrum I. X 0.8. Partially restored ventrally and on each side as indicated by dotted lines. In the 

 basicoronal row there are two plates (restored), three plates in the second row, and four in the third, column 5 origi- 

 nal ing in the seventh row with a tetragonal plate, a rare occurrence, and to compensate for the two sides wanting 

 there are two adjacent heptagonal plates, H, H. Column 6 originates two rows above the fifth with a pentagonal 

 plate, with an adjacent heptagon on its left ventral border. The seventh column appears at the mid-zone, and an 

 eighth column is represented by two plates. All other interambulacral areas of this specimen have six columns of 

 plates. 



Melonechinus septenarius (Jackson). Page 373. 



Fig. 5. After Jackson, 1896, Plate 9, fig. 49. Same specimen as photograph, Plate 51, fig. 10. Holotype. X 1.3. There 

 are four columns of plates in a half-ambulacrum, and seven columns of plates in an interambulacral area. The seventh 

 column originates between columns 2 and 4, a peculiar exception. 



Melonechinus stewartii (Safford). Page 371. 



Figs. 6-8. Drawn from the original specimen which is an external mold, therefore the lettering of the figures is reversed. 

 A photographic figure of a plaster cast of the type is shown in Plate 54, fig. 1, holotype. 



Fig. 6. Half-ambulacrum near the mid-zone. X 3.5. Four columns of plates in the half-area; pore-pairs are in peripodia, 



tubercles on ambulacral and interambulacral plates. 

 Fig. 7. Spines. X 3.4. 

 Fig. 8. Dorsal half of interambulacrum G. X 0.9. Seven columns of plates in the area, the seventh appearing above the 



mid-zone. 



Melonechinus obovatus sp. nov. Page 373. 



Figs. 9, 10. Same specimen as photograph, Plate 54, figs. 2, 3. Holotype. 



l''\K- !>. Structure at the mid-zone. X 2.6. Five columns of irregular plates in an ambulacral half-area. As this is an 

 internal mold, the pores do not lie near the interambulacrum (compare Plate 56, figs. 4, 5). Only three columns of 

 plates occur in an interambulacral area, which is the fewest known as a species character in the genus or the family 

 (pp.417, 444). 



Fig. 10. Dorsal view. X 2.6. Three columns of plates in each interambulacral area; impressions of insert oculars and 

 genitals are all in place. The oculars adorally cover the ambulacra and laterally the interambulacra in part on 

 either side. 



Melonechinus liratus sp. nov. Page 374. 



Fig. 11. Same specimen as photograph, Plate 54, fig. 4. Holotype. X 1.3. Section at the mid-zone, showing five columns 

 of plates in an ambulacral half-area, and eight columns of plates in an interambulacral area. 



Fig. 5 drawn by J. H. Emerton; all others by J. Henry Blake. 



