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 tliat 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 

 witli a series of Metopaster uncatas do not in my opinion amount to even varietal rank, 

 and arc confined to the slightly less developed tumidity of the abactiual 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 uncatus. These 

 are, in my opinion, merely individual diff'erences. 



7. Metopaster cingulatds, 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 Une 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 Une 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 Ime. 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 



