NO. 5 



ORDOVICIAN BRYOZOA BOARDMAN 



IS 



all contained large acanthopores and the walls were broadly amalga- 

 mate. 



Acanthopores are confined to zooecial corners, except in advanced 

 growth stages in which acanthopores are large and have a generally 

 irregular appearance and distribution. Central canals of acanthopores 

 are very small or filled. Mesopores are arranged in an apparently 



Table 4. — General measurements 



Paratypes and topotypes 



Lectotype 



Diameter of zoarium 6.1 



Diameter of endozone 2.2 



Average diameter of zooecial void per 



fragment (longitudinal direction) 0.27 



Acanthopores per zooecium 2.7 



Mesopores per zooecium i.o 



Table 5 — Ontogeny 



Width of 



exosone Axial ratio 



1-8 0.75 



2.0 — 



2.S-2.9 0.54-0.65 



3.1 0.58-0.62 



3-8-3.9 0.48-0.54 



Lectotype 3.9 0.35 



4-0-44 0.45-0.47 



4.6 0.46 



54 0.41 



57 0.35 



8.1 0.32 



9-2 0.34 



9.7 0.26 



10.6 0.21 



Tangential aspect 



Acanthopores small, 

 zooecial walls integrate 

 to broadly amalgamate 



Acanthopores small to 

 large, zooecial walls 

 narrowly amalgamate to 

 broadly amalgamate 



Acanthopores large, 

 zooecial walls broadly 

 amalgamate 



random pattern between zooecia and have walls comparable in struc- 

 ture and nearly comparable in thickness with walls of adjoining 

 zooecia. Some of the smaller mesopores have noticably thinner walls 

 than adjoining zooecia. No diaphragms were seen in mesopores. 



Monticules were not distinguished in all tangential sections, and 

 are generally marked by slight increases in zooecial wall thickness 

 and zooecial and acanthopore diameters. 



Quantitative data. — Tables 4 and 5 above are based on sections of 

 fragments from the lectotype and 20 paratype and topotype zoaria. 

 All measurements are in millimeters. The axial ratio is the ratio of 

 the diameter of the endozone to the corresponding branch diameter. 



