I 
156 OOLITIC OPHIURIDtE. \ 
The fact of its limitation to the upper portion of the Lower Oolites is another ] 
illustration of a former remark that a great break appears to have taljen place in the i 
forms of life which prevailed in the upper, when compared with those which existed in 
the lower portion of the Liferior Oolitic series. ^ 
i 
i 
j 
Ophiijrella nereida, Wri(/Jit, n, sp. Woodcut figs. 39, 40. ; 
■J 
Disk small, irregularly pentalobed, each lobe consisting of a shield-like elevation \ 
Fig. 39. Fig. 40. i 
formed by the radial plates, which are covered by a tegumentary membrane closely ; 
j 
