1040 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Genus CHEIRASTER « Studer. 
Cheiraster Studer, Sitzungsber. naturforsch. Freunde Berlin, 16 Oct., 1883, p. 130; Anbangz. d. Abhandl. d. k. preuss. Akad. 
d. Wiss. Berlin, vom Jahre 1884, p. 49, Taf. IV, figs. 8, a, b, c; Taf. V, figs. 9, a b, c, d, e. Type, Cheiraster gazellx or 
possibly pedicellaris Studer. 
Pontaster (partim) Sladen, Narr. Chall. Exp., I, 1885, p. 610. 
Key to Hawaiian species of Cheiraster. 
a. Pectinate pedicellarise on actinal surface snyder > 
aa. No pectinate pedicellarise. 
b. Abactinal paxillar area bristling with erect spinules. Rays rather short horridusi 
bb. No erect, abactinal spinules. Rays long and slender inops ' 
Cheiraster snyderi, new species. 
Pi. x, fig. 3; pi. xviii, figs. 1 and 3. 
Rays 5. R = 51 mm. ; r = 9 mm. R = 5.6r. 6 Breadth of ray at base (between first and second . 
superomarginals) 8.5 mm. 
Rays long and slender, tapering gradually to an elongate pointed extremity. Disk rather small. ! 
Interbrachial arcs wide and rounded. Lateral wall vertical. The marginal plates form a narrow, j 
slightly raised border to abactinal paxillar area, which is subplane. Pectinate pedicellarise on actinal 
surface. 
Abactinal paxillar area is not uniform, the paxillse being of various sizes, spaced, and rather small, I 
decreasing in size toward tip of rays. Larger paxillse of disk bear 6 to 9 short, papilliform spinelets ' 
surrounding a central group of 2 or 3, or sometimes only 1. Scattered among these are smaller : 
paxillse of all sizes, some with only a single little spinelet, others with 3, 4, 5, or 6, and so on up to \ 
the largest. Paxillse on rays bear 4 to 6 spinelets, usually widely radiating, and on outer half of 
arm a few along median radial area may have a single, central, delicate, conspicuous spinule standing 
erect. Those paxillse on papularium are different from the others, being more ornate, with longer I 
spinelets, which radiate to form rosettes. Midway between center of disk and margin, on each inter- j 
radial line, is a single enlarged paxilla with 20 to 25 spinelets. One of these is situated adcentrally to 
the madreporic body. Papulse are large and confined to an oval area at base of rays (papularium), ; 
there being about 25 to 30 of them, distributed in 4 irregular longitudinal rows, the 2 medium series I 
longest. 
Marginal plates form a slightly raised border to disk and rays, which have vertical sides. Plates i 
of lower series alternate with those of upper, except on outer third of ray, where they very nearly 
correspond. Superomarginal plates, 33 in number (in cotype) from median interradial line to ! 
extremity of ray, are about as high as broad, except in interbrachial arc, where the height is much the I 
greater. They are slightly tumid, form a rounded margin, and the prominent transverse sutures follow 1 
an oblique course, trending from within outward and orad. First superomarginal smaller than sue- j 
ceeding ones. Each superomarginal bears 1 short, sharp, cylindrical, tapering spine, at about the 
center of plate. These diminish in length as they proceed outward and are usually absent from the ;i 
first superomarginal and reduced in size on second. General surface of plates is covered with small, j 
rather widely spaced papilliform spinelets. There is a small abnormal, odd interradial superomarginal j 
in one interradius. 
Inferomarginals form a rounded and conspicuous border to the actinal area, on which their 
breadth exceeds their length, on inner half of ray, while the reverse is true for outer half. Each plate jj 
bears a lateral, cylindrical, tapering, sharp spine, 3.75 mm. long, situated near outer or upper margin 
and pointing horizontally out from ray. These spines diminish in length as they proceed outward, | 
and are reduced to about half usual size on first 2 inferomarginals. Below each spine, in a rude semi-- j 
circle, is a group of 3 or 4 spinules similar to but smaller than the lateral spine. One of these is larger j| 
a Ludwig (Mem. Mus. Comp. Zool., vol. xxxil, 1905, p. 1) has united Cheiraster Studer and Pontaster Sladen (as 
restricted by Perrier). Pectinate pedicellarise can not be used as a generic character, for they may be lacking in species 
normally haying them. I have followed Ludwig. Cheiraster liorridus and Cheiraster inops would, belong to the restricted 
genus Pontaster , according to those authors who prefer to recognize Pontaster as distinct. 
tin the description the proportions have been taken from the cotype, since tip has been broken from all the arms oi 
the type, which is a considerably larger specimen, r = 11.25 mm. 
