64 VERRILL 



rows. Interactinal and subraarginal spines form five or six, mostly 

 double, crowded rows, with about eight to ten in each transverse 

 range, in the adult. Proximal adambulacral spines much elongated. 

 Size large. 

 E. acanthostoma Ver., nov., p. 165. Alaska. 



FF. The dorso-Iateral spines, or groups of spinules, and more or less of the 

 plates, have an evident arrangement in longitudinal rows. Inter- 

 actinal plates present or rarely absent ; seldom more than one row. 



J. Dorsal plates strong, lobate, reticulated so as to form rather obvious 

 longitudinal rows; papular areas usually large, often nearly rec- 

 tangular. E^ch of the principal plates usually bears a single rather 

 large spine, rarely two, forming three to five or more dorsal rows 

 of spines ; smaller spines may occur on the intermediate transverse 

 ossicles. Marginal plates stout, bearing regular rows of spines, 

 much like the dorsals. A row of similar peractinal plates, usually 

 bearing a simple row of spines, often spineless, rarely lacking; some- 

 times a short row of subactinals proximally. Adambulacrals usually 

 diplacanthid, sometimes subdiplacanthid. Major pedicellarias large ; 

 usually of two or more kinds ; the larger dermal ones denticulate, or 

 unguiculate. Rays five or six. 

 Genus Orthasterias Ver., nov., p. 168. Type, O. columbiana Ver., 

 sp. nov. 



K. A row of interactinal plates is present, with or without spines ; they may 

 be small and not visible unless dermis be removed. 



L. One row of peractinal spines, at least proximally; inferomarginals with 

 two rows, making three ventral rows altogether. 



a. Rays normally five, rarely six, elongated. 



b. Dorsal spines in at least five rows, besides some intermediate scattered 



ones on the connective ossicles; papular areas rather small; dorsal 

 radial plates rather large and thick, firmly united. 



c. Five dorsal radial rows of spines obvious. 



d. Apical oral spines not notably enlarged. Dorsal spines obtuse and fluted. 



Wreaths of minor pedicellariae on thick dermal-sheaths, often above 

 the middle of the spine. 



e. Adambulacral spines flattened; adoral spines longer, not very slender; 



dorsal spines obtuse or truncate, rough or fluted. 



O. columbiana Ver., sp. nov., p. 168. Vancouver I. to Yakutat, 

 Alaska, 

 ee. Adambulacral spines all very slender and subequal ; regularly diplacan- 

 thid, strongly and evenly divergent, thus forming two remarkably 

 regular pectinate rows, those of the inner row usually horizontal. 



O. biordinata Ver., nov., p. 173. British Columbia. 

 dd. Apical oral spines notably stronger than others. Dorsal spines tapered, 

 not fluted. Minor pedicellariae are notably minute, forming dense 

 basal circumspinal wreaths. Major pedicellariae are very large, 

 stout, often as thick as spines, wedge-shaped, erect, often dentic- 

 ulate. 



O. californica Ver., nov., p. 174. California. 



