THE STAREISHES OF THE HAWAIIAN ISLANDS. 
1103 
including the marginal, overlies the upper end of those of the next series below, while the aboral 
edge of each plate underlies the adoral edge of the succeeding plate in a longitudinal series. At base 
of ray most of the lateral series are confined to side of ray, only the lowermost taking any part in the 
actinal surface, but toward the middle of the ray the latter series gradually diminishes in size and 
ends, and the second series is adjacent to the adambulacrals. In outer third of ray second series dies 
out, so that then only 3 series intervene between the marginals and adambulacrals. All of the plates 
are very slightly convex, and the 2 lowermost series are slightly smaller than the 3 upper, all of which 
are a trifle smaller than the (supero-) marginal series. Pap u Ire are in regular rows between successive 
series of plates, single, except near base of ray, where there may be 2 or 3 to a pore. Surface of all 
plates is covered with numerous, delicate, short, papilliform, spinelets, each invested by a thin mem- 
braneous sheath, which is frequently swollen to resemble a slender miniature barley-grain. These 
spinelets are articulated to granular protuberances on the surface of plates, and, though numerous, 
are distinctly spaced. They form a rather coarse nap all over the surface. The medioradial plates 
are submammilated, and surmounted by a short, stumpy, conical spine. In extreme cases there is a 
definite carinate ridge along the medioradial line, each plate being surmounted by 1 to 3 short, cylin- 
drical, blunt spines or tubercles. Superomarginal plates are not prominently mammilated as in the Z. 
diomedx type. In neighborhood of papulae are small, very inconspicuous, forficiform pedicellariae 
scattered among the spinelets. They are larger and more numerous at base of rays and on disk. 
The superomarginals, and plates of all intermediate series between them and adambulacrals, each 
bear a delicate central spinule much longer than the surrounding miliary spinelets. These spinelets 
dimish in size toward adambulacral furrow. They are usually bent upward, appressed to side of ray, 
and are articulated to a granular boss on the plate, being surrounded by a number of miliary spinelets 
and several small pedicellariae. 
Each alternate, adambulacral plate is developed into a prominent ridge, which extends into 
furrow, and separates neighboring tube-feet. The other plates do not have such a ridge. Arma- 
ture consists of 4 rather long, cylindrical, tapering spines, 2 directed into furrow and 2 standing on 
actinal surface. On distal half of ray the outer spine is much reduced or wanting. The series is 
disposed in single file along the ridge, and the innermost spinule is rather the most delicate. This is 
usually directed obliquely and adorally toward center of furrow, and bears at its tip a curious mem- 
branous expansion, sometimes subcircular in outline, around the periphery of which are arranged 
5 to 8 small forficiform pedicellarire, usually graduated in size. These frequently extend down the 
side of the spinule, the largest pedicellariae being nearest the tip. The second spine is also directed 
toward center of furrow, but aborally, and bears on its basal portion a giant forficiform pedicellaria, 
often considerably longer than spine itself. Occasionally 2 pedicellariae are borne on the second spine, 
in which case both are smaller than when there is only one. Again, the third spine has a pedicellaria, 
but this is not usually the case. On the outer part of each plate 1 or 2 miliary spinelets and a pedicel- 
laria are usually present. This extra spinelet is always much shorter than the 2 actinal spines. The 
intermediate adambulacral plates bear a mobile, tapering spine on the edge of furrow, about equal in 
length to the third spine of prominent plates. External to this is a much smaller spinule, which 
stands in a longitudinal series with outer spinelets of prominent plates, and near its base is a small 
pedicellaria. Well within the furrow is a small spinelet, just abactinad from the larger, which, except 
at base of ray, usually bears 1 or 2 small pedicellarire. Occasionally the place of this spinelet may be 
taken by a single pedicellaria. 
Actinostome is deeply depressed, the mouth plates being entirely within the cavity. Their arma- 
ture consists of 3 or 4 robust, slender, slightly flattened spines at each angle. The innermost pedicel- 
larire are very prominent. 
Madreporic body small, with few irregular coarse striations; situated just outside a large interradial 
(basal) plate. Anal opening small, situated just to left of dorsocentral plate. The tube-feet form ‘4 
close-set rows at base of ray; less obviously 4 on distal half. A prominent plate of one side of the 
furrow is opposite an intermediate of the opposite. 
Variations: The most important variation from the type is that of a full-grown specimen which 
has regularly 5 spines on the prominent adambulacral plates, the third in addition to the second car- 
rying a large pedicellaria. A small spinule in the type forms a fifth member to the series, but only 
rarely does a pedicellaria occur on the third or inner actinal spine. Another specimen has a very 
prominent median radial series of mammilated plates, each of which is surrounded by 1 to 3 stumpy 
spinelets. In this specimen the superomarginal plates are slightly more prominent than is usual, but 
F. C. B. 1903, Pt. 3—22 
