1094 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
pointed. The accompanying spinelets appear a trifle larger and stouter in proportion to spine. The 
furrow spinelets are slightly stouter than in de Loriol’s specimen, and there is usually but 1 acicular 
spinelet accompanying the actinal adambulacral spine. De Loriol does not mention the furrow 
pedicellarise, which are present in the Hawaiian specimen. Some of these differences, all of which 
are slight, may be due to age, but more likely to the widely separated localities. 
Valvasler striatus in another widely distributed form. It is found at Mauritius, but there is a great 
scarcity of records for points intermediate between that island and the Hawaiian group, for I have been 
unable to find any. 
Family MITHR 0 DIID 4 i Perrier, 1894. 
Mithrodidaea Perrier, Exp6d. Travailleur et Talisman, Echinodermes, 1894, p. 4. 
= Mithrodiinae Viguier, Anatomie du Squelette des Stell6rides. <Arch. Zool. Exp<5r. et G6n6r., t. vix, 1878 (1879), p. 128. 
Genus MITHRODIA Gray. 
Mithrodia Gray, Ann. N. H., ser. l.vol. Vi, 1840, p. 287. Type, Mithrodia spinulosa (—Asterias clavigera Lamarck). 
Heresaster Michelin, R§vue Zoologique, 1844, p. 173. 
Mithrodia bradleyi Verrill. 
PI. XXXVI, figs. 1, 2; pi. XXXVII, figs. 1, 2, 3. 
Mithrodia bradleyi Yerrlll, Trans. Conn. Acad., vol. 1, 1869, p. 288. 
Mithrodia clavigera Perrier, Revision des Stellgrides, 1875, p. 817; see also p. 337. J. E. Ives, Proc. Philad. Acad. Sci., 1889, 
p. 171. 
This peculiar type is a rather common inhabitant of coral sand and rocks in shallow water, but so 
far as our experience goes is not found on exposed reefs anywhere in the Hawaiian group. Nearly 
all the specimens were taken with hempen tangles . from bottom too rough for dredging 'nets. On 
account of the stout, rough spines with which the sides of the body are beset this method of collecting 
proved very successful, a considerable number of perfect specimens having been secured. These 
exhibit some variation not altogether due to difference of age. 
The largest example has a major radius of 230 mm., or a diameter of about 450 mm. Not all the 
rays are of equal length, one being larger than all the rest. The shortest ray is about 198 mm. 
Inequality of rays seems to be a characteristic of the species. There are generally 5 rays, but one 
small specimen has 4 and another 6. 
Rays aubcylindrical, broader than high, except in young specimens where dimensions are nearly 
equal; distinctly narrowed at base and constricted next to the very small disk. R=about 14 r, but in 
one large specimen the ratio is as low as 1 to 8.5 or 9. The whole animal is covered with a tough 
integument beset with rather sharp granules, beneath which are the plates, so arranged that the 
surface of the body is marked off by coarse ridges forming a sort of network, which isolates triangular, 
roundish, or irregular areas containing the papulae and covered with tiny scattered granules. The 
ridges are thrown into little knobs or prominences which vary considerably in number and 
proportions. As a rule they are more numerous in large specimens, often so much so as to destroy 
the mesh-like appearance of the ridges, which are covered with low, conical, crowded granules that 
give a very rough, rasp-like texture to surface. There are no prominent spines on the dorsal surface 
except in young specimens and very rarely in medium-sized specimens. In the former there is 
usually a median radial series of 61 or 8 widely spaced, rigid, subconical, or elongate thimble-shaped 
spines covered with sharp, scale-like granules. The granules or asperities on summits of the dower 
knob-like eminences, . as well as those of the spine-tips, are larger and sharper than the others. 
There are regularly in old and young 3 longitudinal rows of cylindrical rigid spines, like those just 
described, on either side of the body, 1 on the margin or lateral face of ray, and the other 2 on the 
actinal surface. In adults the spines of the lateral series are least numerous, while those of the 
innermost ventral series are most numerous as well as slightly the smallest. In small and 'medium- 
sized examples there is not much difference between the middle (or outer ventral) and inner series, 
while in some adults there is considerable difference. These spines are slightly tapering and the 
membranous integument covering them is invested, like that of remainder of body, with squamiform, 
a Although Perrier considered this an independent family in 1S84 (M6m. sur les Etoiles de Mer, p. 164), he wrote the 
name “Mithrodin®.'-’ 
