NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
47 
3. Normally developed, they form, according to a process explained by Calvet 1 
and by Waters; 2 one, two, rarely three, distal zooecia. Moreover, the coalescence 
of many buds is often necessary for the formation of a zooecimn or of an inter- 
zooecial heterozooecium. 3 
Similarly 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 areolae 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 
Hypostege 
Endocyst 
Skeleton 
Endocyst 
Ectocyst 
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 hypostege 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 lines the interior of all zooecia, sometimes very thin and 
transparent and sometimes quite thick. It is formed of scattered elements, quite 
1 Calvet, Contributions a l’historie des bryozoaires ectoproctes marins, Travaux de l’lnstitute de 
1’UniversitS de Montpellier, new ser., Memoire No. 8, p. 389. 
2 1906. Waters, Bryozoa from Chatham Island, Annals Magazine Natural History, ser. 7, vol. 
17, p. 18. 
3 1888. Jullien, Mission seientifique du Cap Horn, p. 56. 
