548 PROP. W. J. SOLLAS ON SOME FOSSIL SPONGES 



Hexactinellid sponges which occur with them, their skeleton now 

 consists of crystalline carbonate of lime. 



Peromelia Metabronnii, sp. nov. (Plate XXI. figs. 26 & 27.) 



Sponge of variable form, elongate cylindrical, conical, or obconic ; 

 simple, or bearing a second individual budded off laterally. Central 

 or gastric cavity extending a variable distance towards the base, 

 sometimes nearly the whole, sometimes only half way. Thickness 

 of walls variable, often equal to about half the diameter of the 

 central cavity. A measurement taken midway between base and 

 summit gave in one instance 0-1 inch as the thickness of the wall, 

 and 0*2 inch as the diameter of the cavity. In some the wall 

 diminishes in thickness upwards towards the oscule, which is in the 

 centre of the summit ; in others, on the contrary, it increases in 

 this direction : in the latter case a measurement gave -^ inch as 

 the diameter of the oscule and the same as the thickness of the 

 wall ; in the former 0*24 inch for the diameter of the oscule and 

 0*03 inch for the thickness of wall. The sponge is attached at the 

 base, which sometimes grows out into a thick foot. 



Skeleton an irregular Lithistid-like network, composed of fibres from 

 0*005 to 0*01 inch diameter, consisting of large quadriradiate and 

 triradiate spicules, with rays from 0-005 to 0*01 inch long and 0*0005 

 to 0*001 inch in diameter. On the gastral face of the sponge-wall 

 and in its plane the fibres become flatter and thicker, and the 

 meshes are reduced to oval foramina ; on the exterior no change is 

 apparent, and an epitheca has not yet been observed. Besides the 

 central cavity, and a tendency to the formation of lacunar spaces in 

 the skeleton, at right angles to the sponge-wall, no canal-system is 

 present. 



The specimens from which the above characters are taken are 

 very similar in macroscopic character to Spongites Bronnii of the 

 White Jura, as figured by Quenstedt (Petrefact.Taf. cxxiv.figs. 1-15), 

 but present certain (possibly accidental) differences, such as the 

 absence of an epitheca and of longitudinal ridges on the gastral 

 surface, which render it desirable to distinguish them by a different 

 specific name. Our fig. 26 is similar to Quenstedt's fig. 1, plate cxxiv., 

 representing his S. Bronnii gemellus. Our other specimens may be 

 mostly matched by one or other of the seven figures (figs. 6-9 and 

 13-15) by which Quenstedt illustrates the species S. Bronnii. 



Log. Burton Bradstock. 



Hor. A. Parfcinsoni-zone. 



Peronella repens, sp. nov. (Plate XXI. fig. 31.) 



Sponge consisting of slender pipe-like individuals, which proceed 

 as branches from a thicker procumbent stem, and subsequently 

 remain free or unite laterally by anastomosis, terminating by 

 rounded ends, in the centre of each of which is a circular oscule. 

 The oscule is the open mouth of a cylindrical axial cavity, which 

 extends continuously throughout the sponge. The diameter of the 

 branches is 0-13 inch, of the central cavity 0*043 inch. Skeleton 



