ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER 73 



Although this species resembles a large Hydrasterias improvisa (Ludwig), the 

 latter lacks entirely the actinal plates which characterize even quite small Anie- 

 liaster. Improvisa has numerous small straight pedicellariae on the furrow face of 

 the adambulacrals. These are not found in any of the known forms of Anteliaster. 



ANTELIASTER MICROGENYS, new species 



Plate 30, Figures 1, la-le; Plate 35, Figure 3; Plate 36, Figure 1 



Diagnosis. — Rays 5, rather short, strongly inflated at base, bluntly pointed, 

 recurved; disk fairly large; abactinal skeleton irregular with two rows of meshes, the 

 outer rather elongate transversely; superomarginal and infero marginal plates well 

 spaced, with slender connecting ossicles between the two series; one series of actinal 

 plates, mouth plates small, with two actinostomial and four larger superficial spines; 

 adambulacrals with proximally five, distally three spines in transverse comb. No 

 straight pedicellariae. R 30 mm ± ; r 7 mm. ; R = 4.3 r ; breadth of ray at base, 7 mm. ; 

 just beyond base, at widest part, 9 mm. 



Description. — The abactinal surface might be described as of an indifferent 

 Pedicellaster type, with the usual irregular skeleton, having, however, large trans- 

 versely elongated meshes mostly devoid of papulae, except on disk. The spinelets, 

 generally one to a plate, are a little thicker than usual, about 0.5 mm. long, somewhat 

 tapered, and terminated by several points. (PI. 30, fig. la.) Alternating with the 

 spinelets, and occurring also on the membrane of the meshes, are numerous small 

 pedicellariae about 0.3 mm. long. In alcohol, the spinelets and skeleton were covered 

 by a thickish membrane. 'The sides of the rays are characterized by the regular, 

 rather widely separated marginal series, each plate bearing a single tapered spinelet 

 slightly larger than the abactinal spinelets, and in addition most of the long inter- 

 marginal ossicles of the proximal half of the ray carry also a small spinelet. A row 

 of actinal spinelets, a trifle bigger than the inferomarginal spinelets, extends two- 

 thirds to three-fourths the length of ray. Each intermargiual and actinal mesh (except 

 near end of each series) has a papula. 



An analysis of the skeleton shows an irregular carinal series of four-lobed plates; 

 proximally two dorsolateral longiseries of alternately A and Y shaped plates joined 

 in series by the arms. The handle is connected, respectively, to the carinals and 

 supermarginals, usually by means of one or more slender ossicles. The superomar- 

 ginals are joined to the corresponding inferomarginal by a slender, long ossicle, and 

 the first few inferomarginals are similarly connected to the corresponding actinals 

 by a short intermediate ossicle. (PI. 30, fig. 1.) 



The adambulacral spinelets, 1.5 to 2. mm. long, are proximally five to a plate, 

 in a transverse slightly curved comb. Beyond the basal third of the ray the number 

 is quickly reduced to three which is maintained to the end. On one ray four is more 

 usual than three. There is not much difference in the length of the spines of a comb; 

 the median of three is likely to be the longest, and when there are four or five, the 

 outermost but one is often the longest. 



The mouth plates are smaller than in coscinactis, and normally the spines cover 

 the surface, overlying the first adambulacral comb, as that overlies the succeeding. 

 The surface of the plates slopes sharply toward the mouth so that the two small 

 actinostomial spinelets aredirected fairly into it, or else across the mouth of the furrow. 



