JAPANESE ASTEKOroEA. 197 



Around the edges of the plate there are one or two rows of short 

 cylindrical grannies of very small size. In a few specimens, one 

 of the grannies of the central area near the external edge of the 

 plate is larger and very prominent, so as to bring about a 

 row of small rounded spines along the external edge of the 

 superomarginals. This series may or may not be continuous 

 through the interbrachial arcs. At the middle of the arms the 

 superomarginals are nearly as high as long, and twice as wide 

 as long. The fasciolar grooves are covered with capillary spinelets. 

 Inferomarginals. — The inferomarginals are very wide and the 

 most prominent feature is that each plate bears at its external edge 

 a single, stout, flattened spines, nearly as wide as the plate is long, 

 and with a constricted base and flattened serrated edge (PL III, 

 fig. 52, 53, 58, 59). The interbrachial pair of inferomarginals bear 

 very small flattened spines with pointed edges, and the next pair 

 usually bear spines intermediate in form between those of the 

 first pair and the remaining plates. The inferomarginals project 

 laterally much more than the superomarginals, and the margins 

 of the body are entirely formed by them. The abactinal surface 

 of the inferomarginals is closely covered with very fine, spiniform 

 granulations, and there is a row of more conspicuous spines next 

 the lateral spine. On the actinal side, the inferomarginals are 

 covered with small flattened, erect scales, which stand well apart 

 from one another (PL III, fig. 58). There is also an irregular 

 transverse series of 2-4 slender spines, besides a closely set 

 group of larger and more conspicuous spines at the base of the 

 lateral spine, of which the two or three immediately next the 

 latter are conspicuously larger. The transverse grooves between 

 the inferomarginals are naked. 



