u Farringdon {Coral-Bag) Sponges.'" 433 



of Brunswick (see his illustration, ( Handbuch, &c.' p. 190, 

 fig. 108). 



On grinding down a slice of the Farringdon Peronella du- 

 mosa for microscopic examination, I was gratified to see that 

 it presented triradiate spicules, something like those of the 

 preparation of P. multidigitata sent me by Prof. Zittel, to which 

 I have alluded ; but, to my great perplexity, I also saw that 

 they were accompanied by an unintelligible mixture of incon- 

 gruous forms like those represented by Mr. Sollas in his genus 

 "Catagma " (Annals, 1878, vol. ii. p. 356. fig. 1, and pi. xiv.), 

 whose species also belong to the so-called " Farringdon 

 sponges." 



Thinking, however, that I might find the triradiate spicules 

 (quadriradiate ? for they only loom indistinctly by their trans- 

 parency through the thin slice) strikingly shown in the other 

 preparation to which I have alluded, viz. Peronella cylindrica 

 from the Upper Jura (see illustration, ' Handbuch, &c.' p. 190. 

 fig. 107), I ground down slices of the remaining specimens 

 from Farringdon, viz.: — 1 ; Verticillites anastomans (Zitt. op. 

 cit. p. 190, fig. 106) ; 2, Corynella, sp. ; 3, Oculospongia, sp. ; 



4, Elasmostoma acutimargo (Zitt. op. cit. p. 193, fig. 113); 



5, a specimen like Pharetrospongia [Manon } Sharpe) farring- 

 donensis {op. cit. p. 193, fig 114); and 6, a thick, massive, 

 crenulated, circular, horizontal form about 1| inch in diameter, 

 with square margin, presenting a plurality of deep holes like 

 that of Corynella. 



The result of this examination was as follows: — No. 1, 

 ? Lithistid (it should be remembered that, in addition to the 

 looming indistinctness above mentioned, we must add, in the 

 radiate or branched spiculation, the thinness of the slice, 

 Avhich, although it may not affect the linear form, such as that 

 of Pharetrospongia Strahani, Soil., must, in the radiate or 

 branched spiculation, leave fragments only of the spicules, so 

 that, while the bifurcated ends of a tetractinellid spicule may 

 simulate the radiate, the shaft alone might simulate the mo- 

 nactinellid spicules of a Calcisponge) ; no. 2, ? Lithistid, with 

 large ? bihamates ; no. 3, simply granular, with no appear- 

 ance of spicules ; no. 4, ? Lithistid, branched ; no. 5, linear, 

 flexuous ; no. 6, ? Lithistid, branched. 



Thus the case now seemed to me hopeless, so far as the 

 finding out of the kind of sponges which these fossils repre- 

 sented either generally or specially ; for I could neither see 

 the triradiates so like those of a Calcisponge in Zittel's prepa- 

 ration of Peronella multidigitata, • neither could I see, in any 

 of the linear spicules, the slightest approach in form to the 

 monactinellid one of the recent Calcispongiae, which, to the 



Ann. & Mag. N. Hint. Ser. 5. Vol. iv. 31 



