ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER 75 



genys. The teeth of the vertical series are usually less well developed, and the pedi- 

 cellariae are, of course, smaller (0.18 to 0.22 mm. long; see pi. 29, figs. 3c, 3d, 3e). 



The first two or three adambulacral plates have three slender spinelets, the rest 

 only two, conspicuously longer than the actinals and inferomarginals, which in turn 

 are a trifle longer than the abactinal. The small oral plates each carry three or four 

 spinelets in a series, and the type also has on the outer part of each pair (except one) 

 a large spatulate straight pedicellaria with irregularly denticulate distal margin. 

 These are not present in the other specimen. The spinelets are sheathed in a delicate 

 watery membrane which almost disappears on drying. 



Madreporic body small, at the top of interbrachial sulcus. 



The gonads of the type, a male, are large lobulated organs which open a short 

 distance from the interbrachial angle, just below an inferomarginal plate. The lobes 

 of the gonad extend to the middle of the ray, and fill most of the proximal half of the 

 ray coelom. 



Type.— -Cat. No. E. 1423, U.S.N.M. 



Type-locality.— Station 4770, Bowers Bank, Bering Sea, 54° 31' N., 179° 15' E.; 

 247 fathoms; June 3, 1906; bottom not recorded. The bottom temperature at 

 station 4769, very close to this locality, 244 fathoms, is 38.5° F.; gray sand, green 

 mud. 



Distribution. — -Known only from the type-locality. 



Remarks. — Two small specimens are a hazardous basis for a new subspecies, but 

 they must be treated more formally than variants of the Californian species. Their 

 relationship with microgenys was not at first appreciated, since the presence of large 

 spatulate pedicellariae in one example suggested, rather, coscinactis. The structure 

 of the dorsolateral and marginal skeleton, the form of the spinelets and crossed 

 pedicellariae, and the small size of the oral plates are all more like microgenys than 

 coscinactis. The absence of abactinal papula? on the rays, although not surprising 

 in such small examples, is nevertheless a characteristic also of microgenys. In 

 coscinactis the abactinal papulae extend up to the tip of the ray. 



While the fewer adambulacral spinelets is the most tangible difference separating 

 nannodes from microgenys, the presence of spatulate straight pedicellariae is also 

 probably of value, although these may be present on some specimens of microgenys. 

 The crossed pedicellariae have rather fewer teeth in the vertical series of each jaw 

 and the two or three distalmost are more strongly developed than in microgenys. 



Genus TARSASTER Sladen 



Plate 30, Figures 2, 3; Plate 31, Figures 1, la; Plate 37, Figures 1, la 



Tarsasler Sladen, Challenger Asteroidea, 1889, p. 439. Type T.sloichodes Sladen. — Fisher, 

 1923, p. 252. 



Diagnosis. — Rays 5, slender, tapering, subterete, constricted adjacent to small 

 disk; no actinal plates on ray; inferomarginal plates with a prominent spine heavier 

 than the adambulacral spines and forming a longiseries just external to them; inter- 

 brachial marginals stout, firmly united but not especially enlarged; first pair of 

 postoral adambulacral plates separated or else in partial contact on interradial line; 

 adambulacral plates diplacanthid or both diplacanthid and monacanthid; straight 

 pedicellariae lanceolate, not prominently spatulate or unguiculate; tube-feet quad- 

 riserial proximally, biserial distally. Skeleton a close reticulum of three and four 



