BRYOZOA. 385 



which never present the appearance of vesicular tissue. Dia- 

 phragms horizontal, few in the zocecial tubes, numerous in the 

 mesopoi 



Type: Fistulipora elegans Rominger (F. proporoides Nich.). 

 Range. Hamilton group. 



Sub-order CKYPTOSTOMATA Vine. 



Family CYSTODIOTYONID.E Ulrich. 



Zoaria consisting of two or three layers of cells grown to- 

 gether back to back, forming thin foliate expansions or trian- 

 gular branches. Primitive cells semicordate or obovate-acumi- 

 nate in outline, arranged in longitudinal series between ver- 

 tical double plates. Primitive aperture subcircular, being some- 

 what truncated on the posterior side. As growth proceeds the 

 aperture is drawn out shaft-like, forming a tubular vestibule, 

 and the longitudinal plates become obsolete. Superficial aper- 

 ture with peristome and more or less developed lunarium. In- 

 terspaces between zooecia and vestibules occupied by vesicular 

 tissue, the vesicles more or less completely filled with a minutely 

 perforated calcareous deposit near the surface. Margin of 

 zoarium sharp or rounded, and like the basal portion, non- 

 cell uliferous. 



CVSTODICTVA riridi. Zoaria ramose, .bifoliate, the branches 

 acutely elliptical in cross section, with sub-parallel, sharp, non- 

 poriferous, striated, granulose, or smooth margins. Zoopcia 

 apertures generally arranged in longitudinal series between 

 ridges, sometimes in more pronounced oblique rows. Apertures 

 sub-elliptical, partially closed in the fully matured condition 

 with a more or less developed lunarium, that is always situated 

 upon the side nearest to the margin of a branch. Interspaces 

 finely striated, granulose, or smooth, and never with pits or 

 cells, excepting when worn. 



Type: (.'. ocellntn Tlr.. and ('. piUwti Meek. Range, Upper 

 Helderberg to Coal Measures. 



Cosrixir.M Keyserling, (Coscinotrypa Hall. Zoaria composed 

 of flattened branches, celluliferous on both sides, which inosculate 



48 



