THE ANNALS AND MAGAZINE OF NATUKAL HISTOEY. [FIFTH SERIES.] No. 11. NOVEMBER 1878. XXXVIII. — On the Structure and Affinities of the Genus Catagma*. By W. J. Sollas, M.A., F.G.S., &c. [Plate XIV.] In a previous paper I referred certain kinds of fossil Spongida (Manon macropora, Jerea mutabilis^ Scyphia foraminosa, and others from Upware and Faringdon) to the group of the Renierida (Carter), on the ground that the calcareous fibres which form their skeletons are largely made up of long uni-axial spicules lying lengthwise in the fibre, and so far resemble the skeletal structure of Pharetrospongia. At the same time I was well aware that the fibres of the Faringdon sponges contain other kinds of spicules besides the simple acerates ; but these I then regarded as accidental, and upon consulting Mr. Carter found that he agreed with me in thinking that a Renierid sponge might easily have imbedded some extraneous spicules in its fibres, after the manner of the Hirciniadas, with-out thereby losing its Renierid character. But upon coming to work out these sponges in detail it was soon found that these second sets of spicules, from their abundance and definite position, constituted a peculiar difficulty ; and the fact that Professor Zittel had, upon mature consideration, decided to place the Faringdon sponges with the Calcispongi^ on account of the presence of these particular spicules in them, led me to hesitate before reaffirming ray previous conclusions, and to submit the whole subject to renewed investigation. • Karay/xa, worsted. Ann. & Mag. N. Hist. vSer. 5. Vol. ii, 24
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