METOPASTER CINGULATUS. 53 
conspicuously available for description. To my mind it follows with little doubt 
either that Forbes has described the infero-marginal plates as supero-marginals, 
or else that I have not seen his type specimens. 
With my reverence for all that Forbes has written I prefer to leave the species 
as described by him, together with the record of these remarks, rather than strike 
a ruthless pen through any species created by so careful and accurate a worker. 
Time will pronounce the verdict. 
I consider it quite unnecessary to figure any of the fragments, here referred to, as 
being in the Jermyn Street Collection. The differences they present as compared 
with a series of Metopaster wuncatus do not in my opinion amount to even varietal rank, 
and are confined to the slightly less developed tumidity of the abactinal surface of 
the supero-marginal plates, and to the external contour of the mitrate ultimate paired 
supero-marginal plates, which is slightly convex marginally rather than incurved 
to produce the characteristically claw-shaped form of Metopaster wncatus. These 
are, 1 my Opinion, merely individual differences. 
7. MeETopaAsTeR cincuLatus, Sladen. Pl. XIV, figs. 4 a—4 d. 
Body of small size. General form depressed. Abactinal surface slightly 
concave, actinal surface flat. Marginal contour pentagonal, with the sides slightly 
lunate. The rays are not produced beyond the contour of a true pentagon, and 
the radial angles are not rounded. The major radius is proportional to the minor 
radius as 100: 77°5, the actual dimensions in the example described being, major 
radius 20 mm., minor radius 15°5 mm, approximately. The margin is thick, and 
though well rounded has more or less of a precipitous character. 
The supero-marginal plates are three in number, counting from the median 
interradial line to the extremity, or six from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or “ocular” plate in each case. They 
form a broad border to the abactinal area of the disk of uniform breadth through- 
out, which measures about 6°5 mm. at the median interradial line in an example 
whose diameter (R +r) measures from about 36 mm. to 37 mm. 
Excepting the ultimate paired plates, the four intermediate supero-marginal 
plates on each side of the disk are approximately equal in size, the breadth being 
more than twice and a half the length, the actual dimensions in the example under 
notice being length 2°25 mm., and breadth 6°5 mm., in the plate adjacent to the 
median interradial line. The abactinal surface of these plates is distinctly 
tumid, a subtubercular eminence rising in the median third of the abactinal area 
of the plate. The slope of the tumidity descends gradually on the outer side, and 
8 
