43 



Meliceritites hexagona d'Orbigny. 



Elea hexagona d'Orbigny, Bryoz. Cret. p. 633, pi. 738, figs. 1-4. 

 (PI. V, figs. 3—5.) 



The Zooecia, which are divided by well-developed marginal ridges, are rhombic 

 or hexagonally rhombic, rarely twice as long as broad, and the half-elliptical or 

 triangularly rounded aperture, which is as a rule longer than the suboral area 

 together with the well-developed perislomial thickening takes up the whole breadth 

 in the distal part of the zooecium. While the inter-oral tubercles may be developed 

 in very different degree and may often be quite absent, the supra-oral one is large 

 rounded and forms a robust beak-shaped projection. No distinct oral ledge. The 

 convex operculum presents a distinct flabelliform striation. 



The Heterozooecia, which are spread singly among the zooecia in rather scarce 

 numbers are sometimes only a little longer than the latter, sometimes about twice 

 as long. In the larger of them we may discern in the aperture between a broad 

 proximal part, the lateral margins of which are converging distally, and a narrow 

 distal part of different length with about parallel margins. In the shorter of them, 

 however, the somewhat incurved lateral margins are gradually converging distally 

 in their whole length. The mandible is arched both from side to side and proxi- 

 mally distally. 



Ooecia have not been found. 



No Kenozooecia. 



A Closure effected by means of a flat or concave lamina has only been di- 

 stinctly seen in a small number of zooecia. 



The Regeneration takes place in great measure, and in old colonies many aper- 

 tures are very much projecting because the zooecia have been regenerated several 

 times. There has also be found a regeneration of new heterozooecia in old ones. 



The Colonies. I have examined a number of thick ribbon-shaped two-layered 

 fragments from Vendome (zone with Crania ignabergensis). 



Meliceritites plana d'Orbigny. 



Scmielea plana d'Orhigny, Uryoz. Cret. p. 638, pi. 738, figs. 12-14. 

 (PI. V, fig. 11.) 



The Zooecia, which are more or less regularly rhombic and sometimes more 

 than twice as long as broad, are divided by distinct ridges, and the suboral area 

 which is as a rule more or less convex is much longer; sometimes about twice 

 as long as the aperture. No distinct tubercles. The half-elliptical or triangularly 

 rounded aperture which is a little longer than broad together with the well-devel- 

 oped peristomial thickening takes up the whole or almost the whole breadth in 

 the distal part of the zooecium. No distinct oral ledge. The convex operculum 

 shows a flabelliform striation. 



6* 



