PLATE 30. 

 Palaeechinus quadriserialia Wright. Page 305. 



Fig. 1. Same specimen as photograph, Plate 29, fig. 1. X 1.5. Test elliptical, with four columns of plates in each 

 interambulacral area. In the upper part of the figure the plates are present as indicated by spine tubercles; the 

 lower part is represented by an internal mold of the bases of the plates. 



Fig. 2. Same specimen, from the area marked X in fig. 1, showing ambulacral detail. X 4.3. 



Fig. 3. Same specimen spread out by the Loven method. X 1.5. In the aboral part of the specimen, the plates are 

 present as shown by pores in ambulacral plates and tubercles on interambulacral plates. Parts drawn from the mold 

 of the interior are shown in simple outline; restored portions are indicated by dotted lines (compare Plate 29, fig. 1). 

 Ambulacra narrow, plates all primaries, pore-pairs uniserial. In the basicoronal row of the interambulacra there are 

 two plates in each area, in the second row three plates, and in the third row four plates, excepting in area C, in which 

 the fourth column originates in the fourth row, a rare variation (p. 68). Above this zone no more columns are added. 

 (Compare text-fig. 217, p. 191.) 



Fig. 4. Same specimen, apical disc, restored as indicated by dotted lines. Enlarged X about 3. Oculars are imperforate, 

 and adorally cover the ambulacra and laterally the interambulacra in part on either side. Genitals with three pores 

 each, and secondary tubercles as on plates of the corona. 



Figs. 5-7. Lower Carboniferous, Middleton, County Cork, Ireland (after Wright, 1865, Plate 3, figs, la-lc). Holotype. 



Fig. 5. Four columns of plates in each interambulacral area. X 0.9. 



Fig. 6. The same. Ambulacral detail enlarged. 



Fig. 7. The same. A single interambulacral area. X 0.9. 



Palaeechinus ellipticus M'Coy. Page 307. 



Fig. 8. Same specimen as photograph, Plate 29, fig. 2, holotype. Enlarged ventral border of interambulacrum A to 

 show development; two plates in the basicoronal row, three plates in the second, and four in the third row, the fifth 

 column coming in two rows above the fourth. 



Fig. 9. Same specimen, enlarged X about 1.5. Interambulacrum at the mid-zone with five columns of plates. 



Fig. 10. Same specimen. X 3. Ambulacral detail at the mid-zone, showing two columns of primary plates, pore-pairs 

 \miserial (see p. 308). 



Palaeechinus elegans M'Coy. Page 308. 



Fig. 11. Lower Carboniferous, Hook Point, County Wexford, Ireland. Museum of Practical Geology Coll., London, 6,580. 

 X 6. Ambulacral detail. Same specimen as Plate 31, fig. 5. 



Figs. 1 and 11 drawn by G. C. Chubb; figs. 3 and 4 by A. T. Hollick; the other figures are copies of Wright's figures or 

 of my sketches by J. Henry Blake. 



