28 



with a distinct, but narrow peristomial thickening, and with a well-developed oral 

 ledge the height of which in its distal part may be contained four or five times 

 in the height of the whole aperture. The operculum is convex and provided with 

 very fine radiating striae. No distinct tubercles. 



The Heterozooecia have about the same form and size as the zooecia being only 

 a little narrower, and the chief difference between them and the zooecia is that 

 they are provided with a very small aperture which is either of a somewhat si- 

 milar form or more elongate. They are provided with a well-developed oral ledge 

 and with a more or less distinct peristomial thickening, but their height is some- 

 what variable and may be contained four or five times in the height of the whole 

 heterozooecium. The operculum has a similar structure as that found in the 

 zooecia. 



The Kenozooecia. A somewhat variable number of kenozooecia of the same 

 form and size as the heterozooecia are mixed with the heterozooecia, and these 

 two forms of zooids take up about the one half of the surface in larger or smaller 

 portions of the fragments examined. 



Ooecia have not been found. 



The Closure. I have seen a few zooecia closed by a concave lamina, and a 

 larger number of wholly or partially closed heterozooecia. The closure starts from 

 the edge of the oral ledge, and proceeds in that way that the last part of the aper- 

 ture which is closed is a small median opening distally to the proximal margin. 



The Régénération. I have seen a few zooecia regenerated in old ones. 



The Colonies are free, but I have only seen a number of small (long 4'"'") 

 unbranched cylindrical pieces, each of which contains c. 10 longitudinal series of 

 bryozoids. 



Fecamp (Middle Senonian). 



Meliceritites gracilis Goldfuss. 



Ceriopora gracilis Goldfuss, Petref. Germ., vol. 1, p. 3,'), pi. X, figs. 11a — c. 

 non Meliceritites gracilis Roemer, Verstein. nordd. Kreideg., p. 18, pi. V, fig. 13. 

 non — — Canu, Bull. Soc. Géol. de France, 3e série, t. XXV. 1897, p. 752, pi. XXII, figs. 1—2. 



Meliceritites gracilis Gregory, Cret. Bryoz., vol. 1, p. 324, figs 38a— b. 



(figs, a, b.) 



The Zooecia which are divided by more or less distinct marginal ridges are as 

 a rule rhombical or hexagonally rhombical, and Ihe triangular aperture which 

 takes up the whole breadth in the distal part of the zooecium and rarely attains 

 the half length of the latter is a little longer than broad and provided with a well- 

 developed oral ledge. There is a well-developed peristomial thickening the poster 

 of which forms a prominent lower lip which is often left as a transverse bridge 

 after the rest of the frontal wall has disappeared. The frontal wall is distinctly 

 concave. An operculum has only been found in a single zooecium, 



