6o VERRILL 



L Rays normally five, sometimes varying individually to six. 

 n. Disk somewhat enlarged, thickened or depressed; rays not very slender; 

 spines unequal and uneven; superomarginal row mostly single; 

 inferomarginal row double. 

 o. Disk and rays depressed ; dorsal spines very unequal ; larger ones capitate, 

 forming a prominent median radial row and irregularly linear 

 groups ; ventral spines all rather slender. 

 L. inequalis Ver., sp. nov., p. 117. Orca, Alaska. 

 00. Disk thickened or plump; rays strongly convex; dorsal spines numerous, 

 capitate or clavate, usually areolated, or arranged partly in clusters, 

 often forming a median row ; marginal and peractinal spines thick- 

 ened. 

 L. epichlora (Br.), p. 132 (five-rayed form). Aleutian Is. to Puget Sd. 

 nn. Disk smaller, rays more slender or terete. Dorsal spines subequal, clus- 

 tered, scattered, or somewhat in longitudinal rows. 

 p. Dorsal spines not remarkably small ; not in transverse lateral combs. At 



least one row of interactinal spines proximally. 

 q. Rays very slender, terete ; dorsal spines small, capitate, or clavate, numer- 

 ous, mostly one or two to a plate, not in evident rows. Ventral 

 spines slender, both marginal and peractinal rows single; major 

 pedicellarise large, with long spatulate blades. 

 L. leptalea Ver., sp. nov., p. 119. Virgin Bay, Alaska. 

 qq. Rays less slender. Dorsal spines small, clavate, in about three longitudi- 

 nal rows, not crowded ; both marginal rows regular and distinct, 

 the spines longer and standing singly; interactinal row imperfect. 

 L. arctica (Murdoch), p. 120. Arctic O. ; Bering Sea. 

 pp. Dorsal spines very slender, numerous irregularly arranged ; superomarginal 

 and inferomarginal spines longer, mostly one to a plate, in regu- 

 lar rows. 

 L. epichlora mUiaris Ver., nov., p. 138 (five-rayed form). British 

 Columbia. 

 ppp. Dorsal and marginal spines very numerous, small, subequal, arranged in 

 close clusters, and largely concealed by the large dense wreaths of 

 minor pedicellariae ; marginal plates of both series have two or 

 three small spines, nearly concealed by pedicellariae. 

 Leptasterias obtecta Ver., sp. nov., p. 144. Bering Sea. 

 nnn. Dorsal and dorso-marginal spines very small, numerous, nearly equal, 

 the latter arranged in transverse lines on the narrow ossicles defin- 

 ing large transverse papular areas. Minor pedicellariae small, 

 around bases of spines, not unusually abundant. 

 Ctenasterias cribraria (Stimp.), p. 148. Circumpolar ; Bering Sea; 

 Arctic O. ; North Atlantic. 

 II. Rays normally six, sometimes five or seven ; not autotomous. 

 r. Disk small ; rays slender, not enlarged at base ; papulae few, single or in 

 small groups. Ambulacral pores of the usual size and form, more or 

 less crowded, in four rows. 

 Genus Leptasterias Ver., in part, p. 116. (See above, p. 59.) 

 t. Dorsal spines small, slender, clavate, not crowded nor clustered, pretty 

 regularly arranged in quincunx, surrounded by thick wreaths of 



