250 THE FOSSIL ECHINOIDEA 



List of the Species of Fossil Echinoidea from the Nari Series {Oligocene). 



1. Cidaris, sp. : p. 250. 



2. Ccelopleurus equis, Agassiz : p. 251. 



3. Pratti, d'Archiac if Haime : p. 254. 



4. Forbesi, d'Archiac Sf Haime : p. 256. 



5. Clypeaster simplex, DuMan ^ Sladen : p. 257. 



6. monticulifera, Duncan ^ Sladen : p. 258. 



7. sp. : p. 257. ^ 



8. Eohinolampas difflcilis, Duncan if Sladen : p. 258. 

 9. d'Archiaoi, Duncan S; Sladen : p. 259. 



10. ■ Radakensis, Duncan Sf Sladen : p. 260. 



11. discoideus, d'Archiac: p. 261. 



12. , var. a, Duncan ^ Sladen : p. 262. 



13. , var. /3, Duncan &; Sladen : p. 263. 



14. , var. y, Duncan ^ Sladen : p. 263. 



15. placenta, Duncan ^ Sladen : p. 264. 



16. tumida, Duncan Sf Sladen: p. 265. 



17. , var., Duncq,n ^ Sladen : p. 267. 



18. Euspatangus rostratus, d'Archiac : p. 267. 



19. Schizaster Granti, Ihmean if Sladen : p. 268. 



Total species and varieties, 19. 



III. Descriptions of the Species. 



Order ECHINOIDEA ENDOCYCLICA. 



Family CIBAJRIJD^. 

 Genus CIDAEIS, Klein, 1734. 



1. CiDAKis, sp. Plate XXXIX, Figs. 1 & 2. 



There are three very indifferent specimens of a Cidaris in the collection from the 

 Nari beds ; they are, however, better preserved than the specimens from which 

 MM. d'Archiac and Haime determined their Cidaris Verneuili. This last-mentioned 

 species has given us great trouble, for the description of it is not satisfactory. It 

 was founded upon very imperfect specimens, and the special characters of the form 

 turn out not to be very well defined. The specimens of a Cidaris in the collection 

 now under consideration present some of the characters of C. Verneuili, but careful 

 examination proves that the species are distinct. 



The shape of the Nari specimens is rather low, flat above and below, and rounded at 

 the sides. The median area of the interambulacra is large, broad, and marked with 

 long furrows which reach from the scrobicular margin of the great tubercles to the 

 median sutural line. There is a raised and narrow surface between each pair of 

 grooves which is marked with distant and very visible miliaries, in one row. There is 



