PLOCOSCYPHIA. 135 



The above description is taken from a beautifully preserved fragment of this 

 species presented to the Museum by Prof. Zittel. 



According to Mr. Keeping this species occurs in the Neocomiau beds at Brickhill ; 

 but the figure given is insufficient for me to determine whether the specimen is 

 rightly referred to this species. 



Distribution. Planer-Kalk (Upper Green Sand) : Bannevv'itz, Saxony. Neocomian : 

 Brickhill, Bedfordshire [Keeping). 



Plocoscyphia reticulata, Hinde, n. sp. (Plate XXIX. figs. 3, 3 a, 3 h.) 



Sponge growing in irregularly shaped masses; the convoluted walls, 3-5 mm. in 

 thickness, are disposed so as to form at the surface subcylindrical tubes from 11 to 

 16 mm. in diameter. The outer surface of the wall has a reticulate aspect Irom 

 numerous circular or ovate canal-apertures, 'To to 1 mm. in width, and about their 

 own diameters apart. The canals are blind, and appai'ently are oftentimes curved in 

 their course in the wall. 



The dermal layer is composed of robust spicules with flattened arms and compact 

 nodes ; in places small spines project outwards ; the interspaces are circular. The 

 spicular mesh of the interior of the wall is irregular ; the spicular nodes are -22 mm. 

 apart ; the mesh is subquadrate or circular. 



This species approaches in general appearance very closely to P. pertusa, Gein., 

 but the walls are much thicker and the canal-apertures larger. From P. labrosa, 

 T. Smith, it may be distinguished by its thicker walls and the disposition of the 

 canal-apertures. 



Distribution. Upper Green Sand : Eastbourne. Chloritic Marl : Rocken End, Isle 

 of Wight. 



Plocoscyphia subkuta, Quenst. sp. 



1878. Gyrisponffia subruta, Quenst. Petref. Bd. 5, p. 480, t. 138. f. 2-G. 



Sponges subcylindrical or club-shaped, with rounded summits. An apparently 

 average specimen is 110 mm. in length by 38 in width. The outer surface has 

 numerous circular or ovate apertures from 4 to 10 mm. in width. 



The sponge is composed of convolute walls, 2 mm. in thickness ; the outer surface 

 consists of a spicular network, with definite canal-apertures -75 mm. in width ; the 

 spicular arms are smooth, and the nodes compact. The spicular mesh of the interior 

 of the wall has lantern nodes, the spicular arms are 2 mm. in length. 



Quenstedt states* that Achilleum formosum, Reuss, probably belongs to this 

 species ; but though there is a great resemblance in outer form, the spicular mesh 

 oi A. formosum is composed of spicules with solid nodes, entirely different from those 

 of Quenstedt's form. 



Distribution. Chalk Marl : Rocken End, Isle of Wight. 



* Btihm. Kreide, p. 79, t. 43. f. 7. 



