THE EED CHALK OF HFNSTANTOK. 



471 



and the cells surrounding the " ovicell," I have decided to keep the 

 forms separated. 



Habitat. Oa Lioceramus. Fossill^o. 16ib. 



Horizon. Red Chalk, Hunstanton. 



16. Proboscina Jessoni, sp. nov. (Plate XIX. figs. 7 a, 7 h.) 

 Zoarium fan-like. Colony simple, originating from a disc-like 



cell and between this and the base of the zoarium there is a simple 

 intermediate branch about 1 millim. in length. Out of the upper 

 part of this connecting " link," which may be, really, only a portion 

 of the " egg-cell" (d'Orb.), the true zoarium is developed. The 

 first formed zooecia are in pairs, alternately placed, and then, after a 

 small interval, the colony widens out, fan-like. Zooecia tubular, 

 depressed towards the proximal, raised slightly near the distal 

 extremities ; walls contiguous, and towards the outer margin of the 

 zoarium only the upper portion of the cells is visible. Several of 

 the middle cells of the colony have their orifices closed, and the 

 " closure " is delicately perforated. These probably are the 

 (jonoecia or '' ovicells " of the colony (?). 



Habitat. On Terebratula bijjUcata; unique. Fossil '^o. 15. 



Horizon. Eed Chalk, Hunstanton. 



After I had received from Mr. Jesson by far the larger portion 

 of the one thousand fossils previously referred to, he sent me a small 

 parcel of selected examples, especially drawing my attention to them. 

 *' On some of the fossils," he wrote, " unless I am greatly mistaken, 

 j^ou will find some new forms." Proboscina Jessoni was one of the 

 forms in this batch ; and, as species bearing " closure-cells " are 

 very rare in the lied Chalk, I feel a pleasure in dedicating this 

 species as above. 



Eeuss (Foss. Polyp. Wiener Tertiarbeck. pi. vii. fig. 9) figures 

 and describes a species with a zoarium similar to that of F. Jesson i 

 as Diastopora flabellum, from the marine limestone of Eiseustadt 

 in Hungary. I do not think that the two forms, though apparently 

 similar in habit, could be easily confounded ; for Reuss shows in his 

 fio-ure, and refers to it in the text, that the cells are well separated 

 in the zoarium., whereas in P. Jessoni the walls of the tabular cells 

 are contiguous, not separated, though at first sight they may 

 appear to be so. 



17. Peoboscina gigantopoea. Vine. (Plate XIX. figs, ^a, 8 6.) 

 Reference : Entalopliora gigantopora (Proboscidian stage). Vine, 



Camb. Greensand Polyzoa, Proceed. Yorksh. Geol. Polyt. Soc. vol. ix. 

 1885, p. 8, pi. 1. fig. 3, and vol. xi. 1889, p. 262, footnote. 



Zoarium wholly repent, unbranched. Zooecia very large, tubular, 

 but Escharoidal ; depressed, with large circular apertures, rarely 

 raised above the surface of the zoarium ; surface punctate ; closures 

 occasionally. 



Habitat. On Terebratula biplicata. Fossil No. 20 a. 



2l2 



