TE.MNECHINUS. 285 



The tubercles are large and prominent, though the boss is low ; the coronal 

 plates are high. 



As in Echinometra subangularis there is a flat long-spined variety of 

 Echinometra viridis, distinguished formerly as Echinometra plana, but which 

 the full series now in the Museum collection show r s decidedly to hold the 

 same relation to E. viridis which Heliocidaris mexicana Auct. holds to E. 

 subangularis. 



Same bathymetrical range as former species ; much less common. 



ECHINIDAE. 



Family Echinidae Agass. C. R. Ann. Sc. Nat. VI. 1846. (emend.) 



TEMNOPLEURIDAE. 



Subfamily Temnopleuridae Desor, 1855. Syn. Ech. foss. 



TEMNECHINUS. 



Temnechinus Forbes, 1852. Brit. foss. Tert. Echinod. p. 5. 



Small Echini, test globular, primary tubercles in two principal vertical 

 rows; secondary tubercles irregularly packed round base of primaries and 

 edge of pits situated in median ambulacral and interambulacral spaces. 

 Poriferous zone narrow, confluent, undulating ; pores sunken, tubercles 

 smooth and imperforate, actinal cuts slight, actinal membrane bare. Abac- 

 tinal system prominent, genital plates well developed, genital openings in 

 grooves. Anal system covered by one large conical plate, anal slit on 

 edge of this and covered by three or four small plates. Spines short, 

 slender, somewhat transparent, resembling those of Salmacis ; auricles slen- 

 der and closed. 



