26 Mr. H. J- Carter on the 



is a mixture between that of a Lithistid and a Hexactinellid 

 in a calcareous sponge ! Nor is the structure more like that 

 of a Lithistid (fig. 4) than the general form of this little fossil 

 (figs. 1-3), which, being subcylindrical, furrowed or not as the 

 case may be at the aperture (fig. 2) , and pierced to the bottom 

 by a continuous cloacal canal, into which the larger branches 

 of the excretory system entered laterally (fig. 3), adds to the 



delusion. 



Q 



baculata, to which Zittel has given the generic name of 

 "Peromelia" (No. 8, vol. iv. p. 69), then 8. cylindrica and P. 

 cylindrica are totally different in their spiculation, as Zittel's 

 slide, to which I have alluded, and his representations of the 

 latter, compared with what I have stated of the former, point 

 out — a fact which shows that resemblance in general form 

 alone is no more to be trusted in fossil than in existing 

 sponges, and thus the necessity of studying each form through 

 translucent slices under the microscope to obtain the spicula- 

 tion, which I fear must be long before it is generally accom- 

 plished, since it not only involves the necessity of procuring 

 a favourable specimen, but time and ability, on the part of the 

 operator, if not the employment of a lapidary. What spongo- 

 logist without this would have said that the little fossil form 

 called "Verticillites" had been a Calcisponge, which Dr. 

 Steinmann has virtually denied, evidently for want of a favour- 

 able specimen in which to see the triradiates (No. 13, p. 165). 



I have given several illustrations from the fibre of Scyphia 

 cylindrica^ var. baculata, which for the most part have been 

 drawn under a power of about 300 diameters, with copious mea- 

 surements, so that they may be almost viewed as facsimiles. 



With reference to the " multifid " spicules figured by Prof. 

 Sollas from the fibre of Manon macropora, &c. (op. et he. cit.) 

 and those by Dr. Steinmann from his Cryptoccelia Zitteli 

 (No. 13, p. 177, pi. viii. fig. 5), I can only state that the same 

 kind of fades is presented by slices of the fibre of my speci- 

 men of Spongites from Farringdon (? Spongites sella. No. 7, 

 Taf. exxvi. figs. 58, 59), wherein, however, it is evident that 

 the spiculation is chiefly composed of the common equiarmed 

 triradiate of different sizes, accompanied by modified forms in 

 which the arms appear to be much extended, if not branched 

 also ; while one spicule much larger than the rest often pre- 

 sents itself under the form of a simple straight shaft in the 

 axis of the fibre, like that of Sestrostomella, although not 

 nearly so colossal, being similarly inflated at the extremities, 

 at one of which it may present a short spur, while in other 

 respects they appear to be connected with other shafts of a 



