80 ME. E. A. WALEOBD ON CHEILOSTOMATOUS [Feb. 1894, 



concentric layers of dense ironstone, an evidence also of the early 

 segregation of the iron. Equally well-preserved fossils have been 

 occasionally found, the most remarkable being the leucoid sponge, 

 with its delicate network of spicules, Leucandra Walfordi, described 

 by Dr. G. J. Hinde (Ann. & Mag. Nat. Hist. ser. 6, vol. iv. 1889, 

 pp. 352-357 & pi. xvii.). 



Cisteenipeea, gen. nov. 



Zoarium foliaceous and bilaminate, or erect, ramose, and cylin- 

 drical. Zocecia long, tubular. Aperture ovoid. Ovicell supra-oral. 

 Giant cistern-cells in the zoarium. 



Cisteenieeea inconstans, Walford. (See Quart. Journ. Geol. Soc. 

 vol. xliii. 1887, pp. 633-634, pi. xxv.) (PI. V. figs. 1-8, 16, 17.) 



Zoarium erect, foliaceous, bilaminate, with flattened or cylindrical 

 branches ; or unilaminate and irregular. 



Zooecia radiating fan-like from the base, tubular, lengthened, 

 with proximal ends free. 



Secondary aperture orbicular or ovoid ; tube thin, often lengthened. 



Apertural plate, with central infundibuliform opening, clithri- 

 diate in the early stage ; ovicell-tube opening at the superior border, 

 ovoid operculum at the lower border (PI. V. fig. 1). The plate is 

 pitted here and there, and frequently bears raised openings on the 

 right and left of the central opening. Upper lip of certain zocecia 

 arched, bearing an avicularian cell (PI. V. fig. 2). The ovicell-tube 

 passes through the back of the zocecium, and communicates with a 

 hyaline ovicell, faint traces of which are seen on the walls of the 

 zocecium above (PL V. figs. 3, 6). One or two pores below the 

 lower lip (PL V. fig. 1). 



In another specimen, from which figs. 5 and 8 are taken, the 

 infundibuliform opening varies from the centre to the lower part 

 of the plate, and communicates apparently with a tubule, as in the 

 latter figure. 



Cistern-cells not found as yet on this form. 



The zocecia are separated by raised violet-coloured margins, and 

 bear numerous serried folds down the centre. 



ClSTEENIFEEA INCONSTANS, EOEHA PRIMA.. (PL V. figS. 9-13.) 



Zoarium erect, foliaceous, bilaminate. Zooecia lengthened, 

 tubular, radiating from the base, with long, free proximal ends. 



(1). With an acute and slightly arched upper lip, bearing an avicu- 

 larian cell. Apertural plate, with a central infundibuliform opening 

 and an ovicell-tube opening. 



(2). Apertural plate, with an ovoid opercular aperture near the 

 lower lip, two small central perforations, and an ovicell-tube opening. 

 Peristome raised, thin (PL V. fig. 9). 



(3). Aperture ovoid, with an erect or arched rostrum proceeding 

 from the back, bearing a pore at the apex. Mouth divided into two 



