SHALLOW-WATER STARFISHES 59 



j. Rays five, rather long, rounded. Primary dorsal spines few, short, stout 

 (2 to 3 mm. thick), capitate, forming a median row, with few 

 irregularly scattered ones of similar size and form. Two marginal 

 and two interactinal, regular, mostly simple, rows of short, stout, 

 blunt spines; adambulacrals subdiplacanthid. 

 A. victoriana Ver., p. 102. Vancouver I. 



jj. Rays long, slender, acute; dorsal spines of moderate length, slender, 

 fluted, mostly one to a plate, arranged in quincunx, or in about 

 seven obscure alternating rows; median row with longer spines, 

 distinct; both marginal rows single; peractinal row double, with 

 spines longer than marginals; major pedicellariae adambulacral, 

 rather large, lanceolate. 

 A. namimensis Ver., p. 105. Brit. Columbia. 



ii. Rays normally six. 



k. Dorsal spines very diverse in form and size; primary ones very large, ir- 

 regularly placed, but not acervate, very stout (2 to 4 mm.), with 

 nipple-shaped, sulcated tips; smaller spines numerous, unequal, 

 capitate or round-topped, with abundant minor pedicellariae. Mar- 

 ginal and interactinal spines smaller, in about four close rows 

 proximally; adambulacrals mostly two to a plate; the inner ones 

 and furrow margins bear abundant clusters of small major pedicel- 

 lariae. 

 A. polythela Ver., p. 104. Arctic O. 



kk. Primary dorsal spines not unusually large; not nipple-shaped. 



I. Primary dorsal spines more or less unequal, capitate; the larger usually 



acervate or irregularly grouped. Pedicellariae small, numerous; 

 major ones ovate, forming clusters on the adambulacral spines, a 

 few also on the interactinal areas. One complete row of peractinal 

 spines, separated from the adambulacrals by a naked zone contain- 

 ing papular areas. Subactinal spines form a short series, or may be 

 lacking. 

 A. acervata Stimp., p. 107. Bering Sea; Arctic O. 



II. Principal dorsal spines not very unequal nor distinctly acervate. 



m. Dorsal spines rather small, irregularly reticulated; adambulacrals sub- 

 diplacanthid. 

 A. katherina Gray (non Per.), p. 112. Oregon; Gulf of Georgia. 



mm. Dorsal spines very numerous, in distinst radial rows, not very diverse in 

 size, capitate, several on a plate ; the median row crowded and 

 more or less clustered ; both marginal rows double ; two interactinal 

 rows. 

 A. multiclava Ver., p. 114. Siberia. 



HH. Papular areas small; papulae few, large, mostly standing singly or in 

 small groups of one to five, rarely ten or more. Dorsal plates 

 usually lobed and united by overlapping, sometimes in radial rows. 

 Adambulacral spines alternately one or two to a plate, or else 

 biserial. Minor pedicellariae as in Asterias; large, serrate, dermal 

 ones may occur. Eggs and young usually carried in clusters around 

 the mouth of the mother; genital pores ventral. Size small. Rays 

 normally five or six. 

 Genus Leptasterias Ver., in part, p. 116. (See below, p. 60.) 



