1108 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Genus ODINIA Perrier. 
Odinia Perrier, Ann. Sci. Nat. (Zool.), t. xix, 1885, p. 9. 
Odinia pacifica, new species. 
PI. xliii, fig. 1; pi. xlvii, figs. 1, la-d. 
Eays 17. R = 240 mm. ; r = 13.5 mm. R = 17.7 r, approximately. Breadth of ray at base, 7 mm. ; 
at widest part of genital expansion, from 8 to 16 mm. ; midway along ray, about 6 mm. Rays united 
at base, by marginal plates, for a distance of 7 to 8 mm. from margin of disk. 
Rays elongate, slender, fairly narrow at base; often swollen considerably just beyond the base! 
into a prominent ovarial inflation, the tumidity of which is greatest abactinally. In some cases the • 
swelling is nearly absent, but in others it is very prominent, resembling a big gall. The latter is 
probably artificial, having been produced when the creature was thrust into alcohol. Beyond this 
portion the ray is very slender and gradually tapering, the ambulacral ridge being clearly visible 
through the thin abactinal membrane. Ray is roughly equilaterally triangular in section, the corners, 
of course, being well rounded. 
Disk of fair size, circular, with rather high sides, so that abactinal surface, which is slightly con- 
cave, is raised above base of rays. Margin rounded. Abactinal surface and sides covered with rather 
robust, irregular plates, close-set, in the integument. Plates scattered in central portion of disk. 
Between the plates are large papular pores. Papulae single (one to a pore), large, vermiform, numerous. 
Plates irregularly convex abactinally, and surmounted by 1 to 3 short, round-tipped, untapered 
spinelets (0.50-1 mm. long). Scattered among these are numerous minute, crossed pedicellarise. The 
spinelets are so small that they give scarcely more than a roughened appearance. They are longer on 
the sides of the disk, but there do not exceed 1 mm. in length. Numerous spinelets bear several of 
the microscopic pedicellarise on their sides. Genital region, at base of ray, covered with thin mem- ; 
brane under which are various sized, very irregular, small, loosely imbricating plates, which increase 
in size as they recede from disk, the largest plates being in outer part of genital region. Between the 
plates issue numerous single and generally distributed papulae. The genital region is crossed by rather 
irregular bands of small imbricating ossicles, which are more prominent than those just mentioned. 
These cross ribs are about 5 mm. apart and there are about 6 or 7 of them. They bear a few scattered 
slender needle-like spinules. On proximal third of the inflatable portion of genital region the bands 
are usually very irregular or interrupted; the plates are generally less prominent, and spines are few 
and irregularly distributed, there being none on sides of ray. On the more prominent parts of each 
rib, in the mid-genital region, are 5 very slender spinules on either side, and 2 or 3 others in the mid- 
dorsal region shorter than the rest. The 3 lateralmost spinules are much the longest (4 to 5 mm.). 
All are covered with membrane beset with numerous minute, crossed pedicellarise. (Usually about 
half the spinules have lost the membrane entirely. ) Membrane between the spiniferous ribs closely 
beset with minute pedicellarise like those of disk and spines. These, in fact, extend the whole length 
of ray, and upon the adambulacral plates. Beyond, or distally from the genital region, the abactinal 
surface of ray is covered with thin translucent membrane beset with very numerous, scattered micro- 
scopic, cross pedicellarise, which often show a tendency to collect in irregular clusters or bunches. 
The transverse ribs of the genital region are here represented by prominent lateral keel-like ridges, 
consisting of 5 plates fused together. The missing dorsal portion between two ridges of either side, 
i. e., that portion which would complete the transverse rib, is reduced to an indistinct line of rudi- 
mentary plates, only visible when the membrane is quite dry. The lateral ridges are often not 
exactly opposite on 2 sides of a ray. They are 5 or 6 mm. apart. Just beyond ovarial region, each 
bears 5 lateral spines, which are quickly reduced to 4, and on outer half of ray there are but 3. The 
outer spine, that next to adambulacral plate, is usually longest (8 to 9 mm.), the other two nearly as 
long. The fourth or fifth when present is considerably shorter. These spines are thickly invested 
with a membraneous sheath, the end of which is often expanded into a flap. Rays are united at 
their base by lateral and adambulacral plates for about 7 or 8 mm. from disk. Beyond interbrachial 
angle the lateral or marginal plates may be seen for 15 mm., beyond which point they are only 
evident at the bases of the ribs and lateral ridges. 
Adambulacral plates fairly prominent, forming a rounded margin to the wide furrow. Viewed 
from the actinal side they are broader than long (length 1 mm. approximately). At base of ray 
height of plate as seen from side is about 2 mm. Interspaces or sutures between plates broad. Arma- 
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