37 
fta. Vl.—ECHINOIDK. 
Fig. 27: a, Archieocidaris Wortheni, flattened ; &, Spine of A. Shumardi ; 0, Plate of same ; 
Cidaris Blumenbachi ; e, Melonites (Oligoporus) nobilis;/, Mortonia Rogers!. 
A single form only is known in the Hamilton group, represented 
in Case r, Sect. 2, by a plaster cast. In the Waverly group, Case M, 
Sect. 6, Lcpithchinus is represented by two specimens. In the 
divisions of the Lower Carboniferous Arclueocidaris is represented 
by spines and a few plates, and in Case n, Sect. 7 (bottom), by 
some very fine examples. Melonites is also represented in this 
section, by two very fine slabs, and in the Alcove Case, No. 1 2 
