PHTMAPLECTIA.— EHOPALOSPONGIA. 89 



Phymaplectia scitula, Hinde, n. sp. (Plate XXII. figs. 1, 1 «, 1 b.) 



Sponge funnel-shaped, open below, apparently formed by the coalesced margins of a 

 convolute plate. The walls thin and delicate, between 2'8 and 3-5 mm. in thickness. 

 The only specimen is 38 mm. in height, and 74 mm. in its greatest width. 



The interior of the funnel is marked by very slight elevated spots about 5 mm. 

 apart, towards which closely set minute, radial, open canals, about "4 mm. in width, 

 concentrate. No distinct aperture is to be seen at the centre of these elevations ; the 

 radial canals round some of them are but very faintly marked. 



The spicular mesh is formed of relatively large, closely tuberculated spicules with 

 arms about "35 mm. in length. Very minute spicular bodies also appear to be present 

 between the mesh-pores of the larger spicules, but they are too indefinite for deter- 

 mination. No dermal layer has been preserved. 



The thin delicate walls and the surface-canals of the interior characterize this 

 species. I have only seen a single example, preserved in flint, which belongs to the 

 Jermyn-Street Museum. 



Distribution. Upper Chalk : Wiltshire (Cunnington coll.). 



Genus EHOPALOSPONGIA, Einde, n. g. 



Sponges simple or aggregate, club-shaped, with rounded or flattened summits ; 

 stem simple, with, in some cases, root-like prolongations. 



Neither cloaca nor prominent canals are present ; the sponge is traversed by curved 

 canals of moderate dimensions, which extend from the central portions and open at 

 the surface. Longitudinal canals are present in the stem. 



The spicular tissue is composed, for the most part, of relatively large tuberculated 

 spicules, with straight or curved arms, which connect with adjoining spicules by the 

 interlocking of their tuberculated extremities. In these spicules the tetracladine 

 character can hardly be recognized, but mingled with them in the mesh there are 

 regularly four-armed spicules with smooth arms and tuberculated extensions. No 

 dermal layer has been preserved. 



The mode of growth, character of the canal-system, and the interior spicular 

 structure readily distinguish this genus. In the tuberculate character of the 

 spicules, it resembles Plinthosella, Spongodiscus, and Phymaplectia ; but, so far as 

 I am aware, in none of these genera are smooth-armed spicules mingled with 

 tuberculate forms. 



At present I have recognized two species belonging to this genus, both of which 

 are from the Upper Green Sand. 



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