PLEIOCENE FOSSILS. 



PLATE H. 



ECHINODERMATA. 



Fig. 1. Upper surface of AMPLIIDETUS OKTHONOTUS, a fossil from the Miocene Marl of James 

 Eiver, Virginia ; introduced here for comparison. Unfortunately by a mistake in the 

 position in which this view was taken, the sexual centre appears to be lehind the actual 

 centre of the shell, instead of being lefore it, as in nature. Fig. lc is more correct in 

 this respect. 



" la. Lower surface. 



" 15. Altitude from behind. 



" lc. Profile. 



" 2, AMPHLDETUS AMPLIFORUS, upper surface, page 6. 



" 2a. Profile. 



" 3. AMPHIDETUS GOTHIOUS/upper surface, page %. 



" 3a. Lower surface. 



" 31. Altitude from behind. 



" 3c, Profile. 



" 3d. Magnified view of the minute granulations of the upper surface. 



" Be. View of some tubercles from the lower surface, with a portion of half the next lying ambu- 

 lacrum, less highly magnified than Fig. 3d. 



" 3f. A tubercle from the lower surface, with its shield highly magnified. 



" 4. Enlarged view of part of an ambulacrum of the forward pair, from Agassizia poeifeea, {Plate 

 1, Fig. 5) showing the minute pores of the obsolete half row. 



" 4a. Magnified view of a large tubercle from beside the odd ambulacrum. 



" 5. ECHINO-CIDAEIS, upper surface, as restored from several fragments ; species doubtful. 



" 5a. Profile view of the same. 



" 6. PSAMMEGHINUS EXOLETUS ; a fragment magnified about twice the natural size, j9«#e 4. 



