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 



