PLATE 62. 



Lepidechinus iowensis sp. nov. Page 397. 



Fig. 1. Upper Burlington Limestone, Lower Carboniferous, Burlington, Iowa. F. Springer Coll., 8,010, holotype. Nat- 

 ural size. Five columns of moderately imbricating plates in two interambulacral areas and two columns of low 

 plates in each ambulacra] area. The ambulacra! plates are seen best in area .1. Drawings, Plate 63, figs. 3 and 4. 



Lepidechinus tessellatus sp. nov. Page 397. 



Fig. 2. Upper Burlington Limestone, Lower Carboniferous, Burlington, Iowa. Mus. Comp. Zool. Coll., 3,053, holotype. 

 Natural size. Six columns of rounded hexagonal, moderately imbricat ing plates in each interambulacral area and two 

 columns of low plates in each ambulacrum. Drawings, Plate 63, rigs, 5 and Ij. 



Fig. 3. Same horizon and locality. Mus. Comp. Zool. Coll., 3,004, paratype. X 2. Specimen seen from the interior; 

 ambulacra are wider than on the exterior, six columns of plates in each interambulacral area, and the plates are more 

 sharply hexagonal than on the exterior. Oculars fail to reach the periproct or are exsert, each bearing a pore, and 

 each ocular plate adorally covers an ambulacrum and laterally an interambulacrum in part on each side. Genitals 

 with a single pore in the middle of the plates, a character seen in no other Palaeozoic type (pp. 171, 221). Draw- 

 ings, Plate 63, figs. 7, 8. 



Fig. 4. Same horizon and locality. F. Springer Coll., 8,011, paratype. Natural size. Six columns of moderately im- 

 bricating plates in the interambulacral area and two columns of low plates in each ambulacra] area. Drawings, 

 Plate 63, figs. 9-11. 



Lepidechinus imbricatus Hall. Page 399. 



Fig. 5. Burlington Limestone, Lower Carboniferous, Burlington, Iowa. Mus. Comp. Zool. Coll., 3,055, holotype. X 2. 

 In each ambulacra] area there are two columns of low plates imbricating strongly adorally. In each of the inter- 

 ambulacral areas A and I there are eight columns of plates imbricating strongly aborally and from the center laterally. 

 Drawing, Plate 64, fig. 1. 



Perischodomus biserialis M'Coy. Page 401. 



Fig. 6. Lower Carboniferous, Ireland, probably from Hook Head. Trinity College Coll., Dublin. Natural size. Internal 

 view of the ventral area. Ambulacra] plates are wide and imbricate aborally and bevel over the interambulacrals 

 laterally. Interambulacral plates imbricate adorally ami toward the center. (All this direction of beveling is just 

 the reverse of what is seen on the exterior because it is an internal view. Compare text-figs. 32-34, p. 75.) The 

 primordial interambulacral plates are in the basicoronal row; there are two plates in the second row and three 

 plates in the third row, as seen best in areas A ami G. The fourth and fifth columns originate in succeeding rows. 

 In area J a few ambulaeral plates of the peristome are seen extending beyond the primordial interambulacral 

 plate of area A, compare Plate 23, fig. 1 (p. 404). Drawing, Plate 64, fig. 2. 



Fig. 7. Same horizon and locality. Trinity College Coll., Dublin. Natural size. External view of the dorsal side. Two 

 columns of low narrow plates in each ambulaeral area, imbricating adorally and beveling under the adambulacrals. 

 Five columns of plates in each interambulacral area near the mid-zone, the plates imbricating adorally and from the 

 center laterally and over tin' ambulacrals. Two of the median columns drop out. passing dorsally in each area. Ec- 

 centric primary tubercles are seen on adradial and some other interambulacral plates (p. 404). Drawings, Plate 64, 

 figs. 3-6. 



Figs. 1 and 4 from photographs by F. A. Saunderson ; tigs. 2, ::, and 5 by H. W. Tupper; figs. 6 and 7 from photographs 

 taken by A. C. Bridle in Dublin. 



