78 VERRILL 



Dr. Rathbun has sent nearly natural-size photographs of the 

 original type of this species, which seems to be almost unknown in 

 many later collections. 



The disk is of rather large size and elevated ; the five rays taper 

 rapidly from rather wide and swollen bases. The radii are about 

 30 mm. and 116 mm., if the photographs are correctly marked as to 

 reduction ; ratio, about as i : 3.87. 



The adambulacral spines are small and slender, mostly compressed, 

 crowded in one row, one to a plate ; those near the mouth are longer. 



The inf eromarginal and actinal spines are very much larger, rather 

 short and very stout, mostly clavate or subspatulate, and with a 

 deeply grooved or gouge-shaped tip ; but many are simply sulcate and 

 little flattened. They form four or five crowded rows near the bases 

 of the rays, the inferomarginals bearing two spines, but at about 

 the middle they are reduced to three or four regular rows. Most of 

 them bear close clusters of minor pedicellariae on their outer side. 

 The superomarginal spines are smaller, fusiform or subconical, sub- 

 acute; they form a pretty regular row, separated from the infero- 

 marginals by a rather wide channel. 



The dorsal spines are short, thick, nearly equal, with conical, 

 mostly subacute tips. They are rather irregularly distributed, in 

 short broken rows or singly ; they form a somewhat evident median 

 radial series, of two or three close irregularly alternating rows on 

 the basal part of the rays ; on the sides many of them are in obliquely 

 transverse short rows, and sometimes short longitudinal rows can 

 be traced. They bear small basal groups of minor pedicellariae. 

 Dermal minor pedicellariae everywhere scattered between the spines. 

 The sessile, dermal, major pedicellariae appear to be few and mostly 

 along the submarginal channel; they are rather small, short, sub- 

 conic, obtuse. A few lanceolate, acute, major pedicellariae occur 

 along the edges of the ambulacral grooves. 



VARIATIONS. 



This species varies considerably in appearance, according to age, 

 locality, and mode of preservation. When dried carefully, from 

 alcohol, the disk is high and convex, while the mouth and jaws are 

 deeply sunken; the rays are stout and high at base but rapidly 

 tapered. There is usually a distinct median dorsal row of spines, 

 simple in the younger specimens, but often double- or triple-ranked 

 in the older ones. 



