PHYMATELLA. 59 



lower portion. It is 43 mm. in width ; the cloaca is cylindrical, about 12 mm. in 

 width, and extends nearly to the base of the sponge. The exterior surface is thickly 

 covered with numerous irregularly disposed canal-apertures 1 mm. wide ; the canals 

 extend in a nearly horizontal direction towards the centre of the sponge. The four- 

 armed spicules are slender with inconspicuous nodules. The specimen is preserved 

 in Chalk, and the spicular structure has been changed into reddish peroxide 

 of iron. 

 Listribution. Upper Chalk : South of England. 



Phtmatella heteropoea, Roemer, sp. 



1840. Scyphia heteropora, Roem. Nordd. Kreide, p. 7, t. 3. f. 13. 

 1878. Phymatella heteropora, Zitt. Studieu, II Ab. p. 74, t. 8. f. 2. 



Detached spicules of the body and surface-layer of this species. 

 Distribution. Upper Chalk: Biewende, Brunswick [ZitteVs coll.). 



Phtmatella reticul.\ta, ITinde, n. sp. (Plate XI. figs. 1, 1 «, 1 b.) 



Sponges massive, either cylindrical, club-shaped, or obliquely turbinate, with a 

 depressed conical or truncated summit. The lower portion of the body gradually 

 tapers to a cylindrical stem, which terminates in a branching root. In some 

 specimens nodose or spur-like projections are irregularly scattered over the surface. 

 The surface exhibits a coarse irregular reticulation. There is considerable variation 

 both in the size and form ; cylindrical specimens reach a length of 320 mm. by 

 72 mm. in width ; the turbinate examples, though not so long, reach to a greater 

 width — one of these is 105 mm. in diameter. 



The tubular cloaca in a large specimen is 24 mm. wide at the summit ; from its 

 margins branching canals radiate down the summit of the sponge. The canals 

 extending from the outer surface to the interior are 1 mm. in width. 



The internal skeletal structure of these sponges has been so greatly altered by 

 fossilization, that it has been very difficult to determine the original character of the 

 spicules. I have, however, been able to discover in a thin transverse section traces 

 of the straight arms and junction-nodes of tetracladine spicules ; the spicular arms 

 are ■225 mm. in length by •033 mm. in width. The outer surface, when treated with 

 dilute acid, also shows indistinct traces of similar spicules. 



These sponges have been referred to Phymatella intumescens, Rocm., sp., from 

 which, however, they are distinguished by their massive walls, the coarse irregular 

 reticulation of the surface, and their generally large proportions. 



Distrihution. Upper Chalk : Flamborough, Yorkshire ; South of England. 



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