126 



between the tubercles ; these excavated lines exist only from 

 the vertex to the widest part of the periphery. Ambulacra 

 with pores disposed in serrated rows ; mouth small, retracted. 

 Recent and fossil. Leske ap. Klein, Tab. x. fig. D. E. 



13. E. pentagonus. Pentagonal and subpyramidal ; the 

 sides nearly flat ; the porous fasciaB with two rows of pores ; 

 the areas, on the upper part, with but few small tubercles ; 

 but, on the lower, thickly set with tubercles surrounded by 

 circles. Fossil, found in the upper oolite. 



This species is very interesting : its form is so decided 

 as to authorise it to be considered as possessing a depressed, 

 obtuse, five-sided subpyramidal form. The upper parts of 

 all the areas are remarkably bare ; but, about the rounded 

 margin, the verrucae, surrounded by rings, as in echinanthus, 

 become frequent, and, particularly over the whole of the 

 base, they are set very thickly, but distinctly, between the 

 interposed biporous bands. 



The descriptions given, by Lamarck, of the following 

 species of cidaris, brought by MM. Peron and Le Sueur, 

 give reason for believing that the recent analogues of more 

 of our fossil echini may be discovered in the South Seas. 



14. E. virgatus. Hemispherical, rather raised ; subven- 

 tricose, assulae apparent ; the middle of the areas thin of 

 tubercles, and striped with violet; the ambulacral bands 

 with three double rows of pores. Recent. Lam. 



15. E. globiformis. Nearly spheroidal ; red or orange 

 coloured, with white-eyed tubercles ; four rows of pores in 

 the areas. Recent. Lam. 



16. E. polyzonalis. Hemispherical, rather depressed ; 

 subpentagonal ; greenish, with transverse white zones de- 

 cussating white porous rays ; the lower surface concave. 

 Recent. Lam. 



17. E. maculatus. Hemispherical ; white, with spots of 

 a greenish yellow disposed in transverse zones ; areas slightly 

 verrucous. Recent. Lam. 



