REPORT ON THE ASTEROIDEA. 647 
of the mature ray of Freyella heroina, are taken into consideration, together with the 
differences in the adambulacral armature and the spinulation of the abactinal plates, I 
consider it safer on the strength of the material at my disposal to rank the form under 
notice as a distinct species. 
Genus Colpaster, n. gen. 
Rays elongate and subcylindrical as viewed from above, having the general character 
of the rays of Brisingidz. Disk small and sharply defined, the rays being readily 
detachable. 
Abactinal area of the disk and of the basal portion of the rays covered with small, 
seale-like, imbricating, calcareous plates, which form a compact casement. The plates bear 
minute isolated spinelets, those upon the disk being slightly larger than on the base of the 
rays, and with their extremity denticulate. No papule are present. 
_ Adambulacral plates only slightly longer than broad, widely spaced, the interspaces 
being filled with ligament. Adambulacral armature consisting of two small equal inner 
spinelets, one at each extremity of the furrow-margin, and two unequal spines on the 
actinal surface of the plate, one large and robust. These are invested with membranous 
sheaths covered with crowded pedicellariz. Robust lateral spines are articulated on small 
rudimentary infero-marginal plates intimately united to the adambulacral plates. 
An azygos interradial plate, shield-shaped and conspicuous superficially, separates the 
first pair of free adambulacral plates, resembling the mouth-shield of an Ophiuran. 
Mouth-plates small, with an armature consisting of three mouth-spines proper, and 
three large secondary or superficial mouth-spines on the actinal surface of each plate. 
Madreporiform body small, subtubercular, prominent, situated near the margin of the 
disk ; striations few in number and simple. Anal aperture distinct, situated excentrally. 
Remarks.—Colpaster resembles Freyella in general habit and in the plating of the 
disk and ovarial regions of the rays. It is distinguished, however, from that and from all 
other forms by the presence of the azygos interradial plate external to the mouth-plates, 
and by the character of the armature of the adambulacral plates and mouth-plates. 
Chorology of the Genus Colpaster. 
a. Geographical distribution :— 
ATLANTIC: One species between the parallels of 20° and 30° N. 
Colpaster scutigerula, from south-west of the Canary Islands. 
8. Bathymetrical range: 1525 fathoms. 
y. Nature of the Sea-bottom: Hard ground. 
