84 VERRILL 



" Rays five, rather broad, with blunt tips ; disc moderately large. 

 Proportion of the diameters, i : 4.25. Ambulacral pores in four 

 regular rows. Ambulacral [adambulacral] spines in one regular 

 row, slender, long (but not longer than the ventrals), not com- 

 pressed, but tapering to a blunt point. Ventral spines in four 

 approximated rows, elongated, scarcely capitate; heads elongated, 

 subtruncate, striated within, and often sulcated along the middle on 

 the outer side, where there are always semicircular clusters of minor 

 pedicellarias. Beyond the ventral spines there are distinct lateral 

 channels. The dorsal spines are uniform in size and distance, being 

 about one-fourth of an inch apart in one specimen, and arranged 

 without order, except in the regular marginal row, which consists of 

 about thirty spines ; and they form no pentagon on the disc. They 

 are one-eighth inch high, and half that in breadth, capitate, with the 

 heads striated and conical, with pinched tips. Around the base of 

 each there is a rather narrow ring of minor pedicellariae. There are 

 no major pedicellarise scattered among the dorsal spines, but a few 

 occur in the lateral channels, similar to those of A. ochracea and 

 capitata, but of smaller size and with narrower valves. Papulae in 

 groups. Diameter, one foot. It differs from A. gigantea in having 

 only five rays, and in other particulars. 



'* Habitat, Coast of Oregon. Mus. Smithsonian." 



Photographs of the types of this species were also kindly sent by 

 Dr. R. Rathbun from the U. S. National Museum. As marked, the 

 photographs give the radii as 24 mm. and 96 mm. ; ratio, i : 4. 



The description by Dr. Stimpson is so good, in this case, that little 

 need be added to it. The upper marginal spines form a pretty regu- 

 lar row; they are about as large as the ventrals, but more conical, 

 and like the dorsal spines in form, though rather larger. The median 

 dorsal row of spines is not often very evident; in some places indi- 

 cations of four or five other longitudinal rows can be seen on either 

 side, so that there may be ten to twelve spines in a very irregular 

 transverse series, but there are no distinct transverse rows. On the 

 distal part of the rays the wreaths of minor pedicellarige, around the 

 spines, become larger and crowded; there are also large clusters of 

 dermal minor pedicellariae scattered over the whole dorsal surface, 

 many of them on the papular areas, besides many single pedicellariae. 



Two very large and perfect specimens of this species are in the 

 Museum of Yale University, collected at Pacific Grove, California, 

 by Professor W. R. Coe, 1901. 



