216 BRITISH JURASSIC SPONGES. 
specimens range from individuals not more than 7 mm. in length to large forms 
45 mm. in length by 11 mm. in diameter. In these latter the cloacal aperture is 
6 mm. in width. 
The skeletal fibres of the inner portion of the wall vary from ‘1 to ‘17 mm. in 
thickness, as measured in a transverse section ; those of the outer surface are ‘°2 mm., 
whilst bordering the cloacal tube the fibres are ‘25 mm. thick. The spicular 
structure is very indistinctly shown ; it consists of three- and perhaps four-rayed 
spicules. Only occasionally can complete rays be distinguished ; one of these 
measures ‘27 mm. in length by ‘03 mm. in thickness. The spicules vary 
considerably in size ; they are irregularly but closely disposed in the fibres in the 
same way as in P. pistilliformis. 
This species is fairly abundant in the Inferior Oolite. In all cases they are 
simple in their mode of growth, though occasionally one individual may have 
attached itself to the surface of another for support. Sometimes they appear 
to have grown on the surfaces of Hexactinellid sponges, for the under surface of 
the expanded base bears the imprint of cruciform spicules like those of the dermal 
layer of Stawroderma. 
As remarked by Professor Sollas, there is a considerable resemblance in the 
form and mode of growth of this species to some of the forms of Scyphia 
Bronnii, Goldfuss, as figured by Quenstedt from the White Jura of Oerlinger and 
Nattheim (‘ Petref. Deutschl.,’ vol. v, p. 183, pl. exxiy, figs. 1—9). The main 
difference appears to be that in this latter form there are, according to Prof. v. 
Zittel, well-developed horizontal canals, which are not present in P. Metabronnii. 
Distribution.—Inferior Oolite. Parkinsoni-zone at the Cliff-section, Burton 
Bradstock (Rev. G. F. Whidborne ; G. J. Hinde), Shipton George (EH. A. Walford), 
Bradford Abbas (R. F. Tomes), Dorset. 
24, PrronipeLLA Wattont, Hinde, sp. nov. Plate XIV, figs. 3—3c. 
Sponges forming colonies of subcylindrical stems, which frequently diverge 
from each other, and give off short, stumpy lateral branches. The main stems 
usually uneven with occasional swellings and nodosities ; the summits are obtusely 
conical or truncate. They range from 20 to 74 mm. in length, and from 7 to 12 
mm. in thickness. The walls are thick, varying between 2 and 4 mm., the cloacal 
tube subeylindrical, from 2°5 to 5 mm. in width; it extends throughout the length 
of the sponge. The aperture is circular or oval, 4 to 5 mm. in width, the margins 
entire. The outer surface in some specimens is fairly smooth, and perforated with 
