104 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



cylindrical bo slightly elavate, and sometimes a trifle curved upward. The actinal 

 channel is a little narrower than the intermarginal. 



The first five or six adambulacral plates are monacanthid; then about five or 

 six are diplacanthid; the remainder alternate more or less regularly with one and 

 two spinelets. The subambulacral spinelets are elavate, a little slenderer than the 

 nctmuis Iml often no shorter; the furrow spines are a little slenderer than the sub- 

 ambulaerals but instead of tapering, as is usual with furrow spinelets, are more often 

 a trifle elavate. One or two pairs of adambulacral plates meet interradially behind 

 the mouth plates. 



Oral spinelets two; a tapering spine at the inner apex of each plate, shorter 

 than the interradial suture; one suboral spinelet similar to the first few subambu- 

 laerals which are slenderer than further along the ray. 



Abactinal papulae mostly single and inconspicuous; intermarginal and actinal 

 (sometimes two series proximally) in twos and threes. 



Straight pedicellariae (pi. 43, figs. 3c-3c) small, in side view ovate, or broadly 

 elliptical, very obtuse, distributed typically for the genus, the largest being the 

 actinal interradial dermal. Front profile of jaw, usually ovate or broadly lanceolate. 

 The dorsal are very small, as are those along the furrow margin. An intermarginal 

 measures 0.27 to 0.33 mm.; an actinal interrarlial about 0.3 mm. 



The sheaths surrounding the abactinal spinelets are rather pulpy and prominent, 

 often contiguous, but the crossed pedicellariae (0.2 mm.) are few, usually only one 

 to three to each spine. The marginal are more numerous but not abundant; the 

 inferomarginal, actinal, and the adambulacral form very small clusters. (PI. 43, 

 fig. 3d.) 



Madreporic body small, situated one-half r from center. 



Anatomical notes. — The hepatic coeca are large and reach nearly to the end of 

 the ray. The intestinal coecum is a rather slender, 2-lobed sac. The gonads open 

 ventrally by a genital papilla close to the interradial line. The ovaries are sub- 

 globular, the eggs large and relatively few (specimen with R 21 mm.). 



The abactinal skeleton consists of an irregular small-meshed reticulum of very 

 numerous small plates without a differentiated series of carinals. At the nodes are 

 mostly three or four lobed primary plates (usually monacanthid) connected by one 

 intermediate, elliptical, often monacanthid, ossicle. The spaces are larger and the 

 plates slenderer toward the end of the ray. The superomarginal plates are four 

 lobed, but at the base of the ray the transverse lobes only may be present on many 

 inferomarginal plates, since the intermarginal and actinal papular areas are very 

 frequently confluent. A second series of small actinal plates (more numerous than 

 the outer series) is irregularly developed at the base of ray, but generally is not 

 spiniferous. 



Type.— C&t. No. E 1496, U.S.N.M. 



Type locality. — Adakh Tsland, Andreanof Group, Aleutian Islands. 



Distribution.— Pribilof Islands, Shumagin Islands, Andreanof Islands. 



Specimens examined.— YiibHoi Islands (St. George and St. Paul), shore, 4 speci- 

 mens. Adakh Island, Aleutian Islands, shore, 32 specimens. Kyska Island, Rat 

 Islands, Aleutians, 9-14 fathoms, 4 small specimens. Sanborn Harbor, Nagai, 



