Mr. F. M'Coy on some new Mesozoic Radiata. 397 be taken for the Amphipeplea involuta of Thompson ; but it may be distinguished from that shell by its being stronger and more ventricose, and especially by its having the whorls placed more to one side, giving it somewhat the form of a Nerita. When full-grown it is more than three times the size of A. involuta. It differs from all the varieties of Limncea peregra in having the spire involuted and placed rather more obliquely, in the more gibbous and ampuUaceous form of the shell, and in being more regularly striated. The animal, too, is much darker, and not so distinctly marbled on the cloak. A shell found by Capt. Brown in Loch Leven, and described and figured in his ' Illustrations of Recent British Conchology ' under the name of Amphipeplea lacustris, appears to resemble this species in form, but it is stated to have the spire with two small volutions, the superior one blunt at the apex, from which we must conclude that the spire is exserted : the shell is also stated to be ^ extremely thin, pellucid and shining ;^ — characters which agree much better with Amphipeplea glutinosa than with our shell. The Gnlnaria lacustris of Leach, to which Capt. Brown refers his species, is quite distinct from the one now described. Mr. Burnett first detected this new Limnaa in the stomachs of trout caught in Loch Skene, and on a second visit to that wild locality, so tempting to the angler, he succeeded in obtaining many fine living examples, for the larger portion of which I am indebted to his liberality. Some of the older individuals are a good deal eroded and perforated, showing that they have other enemies besides the trout. XLII. — On some new Mesozoic Radiata. By Frederick M'Coy, M.G.S. &N.H.S.D. &c. Amorphozoa. Plocoscyphia laxa (M^Coy). 8p. Char. Hemispherical masses about 2 or 3 inches in diameter, formed of short, wide, irregularly contorted and lobed cups, varying from half to I inch in diameter, the walls about 2 lines thick, of a rather coarse irregular spongy texture. On comparison with the figure of Goldfuss, and with authentic specimens from the Essen chalk of his Achilleum morchella, which now forms the type of the genus Plocoscyphia of Reuss, I find the present species distinguished by its much larger, more deeply and widely separated cups, their much thicker walls, and very much more open lacunose structure. The contortion of the
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