79G W. J. SOLLAS ON THE STRUCTURE AND 



Lithistid had been known to Blainvillc in the shape of S. iypum 

 at this early date ; there is a strong a priori improbability about such 

 a supposition ; and what is better, we have certain information w r hich 

 decides this point, since Mr. Woodward informs me that a section 

 of the original so-called S. typum has been prepared and examined 

 microscopically by Mr. Savile Kent, and that this exhibits the struc- 

 ture of a Renierid sponge ; i. e. its skeleton consists of acerate 

 spicules bound together into fibres. This fact, which was known 

 to Dr. Gray, and appears in the MS. correction of his original classi- 

 fication in the possessioir of Mr. Carter, clears up the whole matter. 

 In the first place Siplionia typwm is not a Siplionia at all, since 

 it belongs to the lienierida), while the Siplwnice belong to the 

 Lithistidae, an altogether different order of sponges ; thus the error 

 of Blainville is rectified ; and next, if S. typum be the same thing 

 as Alcyoniwn Jicus, as I firmly believe it is, then Parkinson's mis- 

 take is also indicated, and the clear insight of Guettard, who plainly 

 saw and insisted on the important differences in general structure 

 between Carico'idcs {Siplionia) and Alcyonium Jicus (S. typum), 

 receives at length its true recognition. 



1836. Sowerby. ' Trans. Geol. Soc' ser. 2, vol. iv. pi. 2. p. 340, 

 pi. xvi«. fig. 169. 



In this paper, which is an appendix to Dr. Fitton's memoir on 

 the strata below the Chalk, Sowerby describes and figures specimens 

 and sections of a species which he terms Siplionia pyriformis, 

 Goldf., and which is found in the Greensand of Blackdown. He 

 states that it exhibits as much variety in form as the fruit from 

 which it derives its name. His figures are superb, and beautifully 

 illustrate the general form and structure of the specimens described: 

 they have in consequence been copied by many succeeding authors, 

 too often, I regret to say, without due acknowledgment. 



►Sowerby's S. pyriformis is not spherical or obconical in shape, like 

 Goldfuss's specimens, but more or less conical, and with a general 

 resemblance to S. Jicus, Goldf. ; probably, however, in a type so 

 variable these forms are but varieties of each other. 



1839. Lee, J. E. ' Magazine of Natural History,' vol. iii. new 

 ser. p. 10, figs. 2 to 6. 



Lee describes two species, which he refers to Siplionia, as S. clava 

 and S. anguilla, both forms from the Chalk of Bridlington, Yorksh. 

 Neither, however, appears to agree in general characters with this 

 genus ; and as microscopic structure is not adduced, conclusive 

 evidence as regards their affinities is wanting. A very interesting 

 observation is made, to the effect that whilst the fibres of the roots 

 of these sponges are often perfectly preserved in the Chalk, yet in no 

 instance have they been found attached to a foreign body. This 

 fact strikingly illustrates the similarity in habit between the old 



