FROM THE INFERIOR OOLI1E. 545 



specimens, some portions of the parent rock are to be found, either 

 filling in the central tube and the spaces between the papillae or ad- 

 herent to the foliaceous base. It consists of a matrix of consoli- 

 dated calcareous mud, or calcite, which forms a mosaic of minute, 

 ill-defined crystals. Some parts of the matrix are stained a deep 

 reddish brown by iron oxide, while in places rhombohedra of a deep 

 brown colour externally, and apparently consisting of iron carbo- 

 nate, are strewn through it. Everywhere also remains of calcareous 

 organisms abound in it : Eoraminifera, perforate, imperforate, and 

 arenaceous; Encrinite and Asterid joints, Urchin-spines, fragments 

 of Polyzoa, Catagmid sponge-structure, and molluscan shells, together 

 with occasional Entomostraca ; grains of siliceous sand, on the other 

 hand, appear to be entirely absent. 



Cosoixoporid^. 

 Leptophragma fragile, sp. nov. (Plate XX. figs. 10, 11, 11 a.) 



A thin plate, averaging -1- inch in thickness, bearing on one face 

 circular excurrent ostia, -^ - inch in diameter, arranged, not quin- 

 cuncially, but in longitudinal and transverse rows, giving to the 

 intervening tissue a square reticulate appearance. On the opposite 

 face incurrent ostia, similarly arranged, but alternating with the ex- 

 current ostia, and concealed by an irregular overgrowth of skeletal 

 network. Incurrent and excurrent canals proceed from their re- 

 spective ostia at right angles across the sponge-wall, and terminate 

 caecally. Skeleton Euretid ; distance between the imperforate nodes 

 Yftjj - -ih) i ncn : a g°°d illustration is given by Zittel (Xeues Jahr- 

 buch fiir Mineralogie &c, 1877, Taf. ii. fig. 1). The specimens from 

 which this description is taken are evidently fragments of some 

 much larger sponge, which probably had a more or less vasiform 

 shape. They agree in all recognizable characters with Teoctispongia 

 foliata, as described by Quenstedt (Petrefact. p. 64, tab. 117. fig. 7), 

 from the White Jura (/3), over the Eucoid Bank, under Muhlheim, 

 on the Danube, and possibly belong to that species. I have hesi- 

 tated, however, to adopt Qnenstedt's name, because as yet I have 

 only seen figures and no specimens of his sponge, and more parti- 

 cularly because these figures do not include a magnified represen- 

 tation of the skeletal network, without which certainty is impossible. 



Loc. Burton Bradstock. 



Hor. Upper part of the A. Parkinsoni-zone 



M^AIDEOSPONGIDiE. 



Plectospyris, gen. nov. 



Labyrinthic sponge, formed by winding dichotomizing anasto- 

 mosing tubes. Skeleton Euretid. 



Plectospyris closely resembles Plocoscyphia, differing from it in 

 having the skeletal nodes imperforate, not JVlyliusian. 



Plectospiris elegans. (Plate XX. figs. 12-14.) 



Anastomosing tubes small, ^-g inch in diameter, wall T l inch 



