NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



47 



3. Normally developed, they form, according to a process explained l>y Calvet l 

 and by Waters; 2 one, two, rarely three, distal zooecia. Moreover, the coalescence 

 of many buds is often necessary for the formation of a zooecium or of an inter- 

 x.ooecial heterozooecium. 3 



Similarty with the frontal buds: 



1. Little developed, they form above the olocyst, a second deposit the tremocyst; 

 their fossil remains are the tremopores. 



2. Little developed and only laterally, they form the lateral punctations, the 

 zoarial remains of which are the areolat, of Harmer. visible in Smittinidae, 

 Escharellidae, etc. They engender the superior endocyst. The latter deposits 

 the pleurocyst above the olocyst. and form the interareolar costules. 



Eotocyst 



Endocyst 



Hypoetege 



Endocyst 



Skeleton 



Endocyst 





-Ectocyat 



- Super lor endocyst 



-Parietal endocyst 



8 



FIG. 3. Sketch showing proliferation of the endocyst in theAnasca (A) and in the Ascophora (B). 



3. Somewhat more developed, they form and secrete the skeletal tubules which 

 make up the thick walls of the Acroporidae. Myriozoumidae. Porella, etc. 



4. More developed, they engender the frontal avicularia and the radicels. 



5. Normally developed, they give rise to the complete zooecia heaped up on 

 one another without apparent order as in the Celleporidae. 



The gymnocyst of Levinsen and the cryptocyst of Jullien are not special forma- 

 tions; these are special walls defined particularly by their position. The cryptocyst 

 supports the hypostcge in the Malacostega ; the gymnocyst does not support it 

 at all; these walls may be of olocystal or tremocystal formation. We have pre- 

 served these two terms of nomenclature in the exact meaning of their authors. 



Olocyst. The olocyst linos the interior of :ill zooecia, sometime^ very thin and 

 transparent and sometimes quite thick. It is formed of scattered elements, quite 



1 Calvet. Contributions a 1'historie tics bryozoaires ectoprui-lrs iii;mn>. Travf.ux ile 1'Institute de 

 I'Universite' de Montpellicr. new ser.. Memolre No. 8, p. 389. 



- 1906. Waters, Bryozoa from Chatham Island, Annals Magazine Natural History. SIT. 7, vol. 

 17. p. 18. 



1 1888. Jullien, Mission scientiflque du Cap Horn. p. 56. 



