PLATE V.—Uraster glacialis. 
1.—a, Four valves of p. maxilleforme. 1. Partially developed. 
b, One valve of p. mandibulatze. 
c, Various separate valves of ). forcepiforme. 
2.—a, Single valve of p. maxilleeforme, 
b, Single valve of p, mandibulate. 
3.—One valve of p. maxilleforme, rather different from usual, the maxil- 
lary portion having al. 
4.—a, P. maxillzforme. 
6, Valve of p. forcepiforme, dorsal view. 
5.—Portion of glacial-looking mass surrounding dorsal spines of U. 
glacialis. 
a, Spine cut through as transverse section. 
b, Aggregated p. forcepiforme. 
c, Membranous expansion, containing muscles, &c., for moving the 
calcareous blades. 
6.—P. forficiforme, side view, 
iy 
