250 Mr. T. Edmondston on a new species of Pecten. E. splendidum, Ehr. Coast of Norway, by Ehrenberg. E. racemosum, Ehr. =r Sertularia racemosa, Cavolini. Bay of Naples. VI. Genus Coryne, Gsertner. Polyps without polypidoms ; tentacles all alike, scattered. C. squamata, MuUer. Coasts of Belgium, England, the Baltic, &c. C. aculeata, Wagner. Coast of the Adriatic. • VII. Genus Hydr actinia, nov. gen. Polyps without polypidoms ; tentacles in one row. H. lactea. Van Bened. = Synhydra parasitica, De Quatref . Coasts of Belgium, Normandy, Brittany, the port of Cette ? Bay of Naples. H. rosea, Van Bened. Coast of Belgium. We are not sufficiently acquainted with the genera Echino-chorium"^ of Hassall and Corimorpha of Sarsf to assign their place. We prefer simply to mention them. Unless we are mistaken^ the two proposed genera (Eleutheria) and Synhydra should therefore not be inserted in the zoological system, the one being a transitory form, a larva ; and the other having been already described under another name. ( XXXI. — Description of a new Species of Pecten. By Thomas Edmondston, F.B.S.E. & L. PecSten MacGillivraii, Edmondston. Sp. Char. — Shell orbicular, white, the upper valve with twenty, the lower with eighteen ribs, which, with the interstices, are quite destitute of longitudinal or transverse strise ; each interstice ter-minates in two acute trigonal teeth. This highly beautiful Pecten, which can never be confounded with any other British species, and which, so far as I can ascertain, is equally distinct from any hitherto described, is of a pure snowy white colour, a slight tinge of pink near the umbo on the upper valve alone excepted ; the surface shining with a satiny lustre ; the upper valve is more convex than the lower and has twenty ribs, the lower valve has eighteen ; in both the ribs are rather de-pressed and evanescent towards the umbones, which are acute ; * Annals of Natural History, vol. vii. p. 371. f Beskivelser og jagttagelser. Bergen, 1835.
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