NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



739 



When the ovicell is very thick the tubes appear displaced and more scattered. 

 This is only an illusion provoked by the elongation of the tubes and their diver- 

 gence; at their base they have the normal distance. (See Diaperoecia, clava.) 



The tubes which traverse the ovicell are often closed by a finely porous, cal- 

 careous lamella. 



D x36 



LI2 



FIG. 239. Anatomy of the Diaperoeciidae Canu, 1918. 



A, B. Diplosolen intricaria Smitt, 1871. A. Section through ovicell, X 25, contuiuing ;i large 

 number of small embryos. B. Section of lobe a, of the same ovicell. (After Waters, 1900.) 



C-E. Diaperoecia intricaria Busk, 1875. C. Ovicelled zoarium, X 12 (o, oeciostomei. Alter 

 Harraer, 1915.) D. Transverse section through a zoarium, X 36, showing in the tubes a large 

 number of minute rays with club-shaped hearts, on which there are numerous tubercles. E. Rays 

 included in the tubes, X 250. 



F. Diaperoecia rugosa Waters, 1878. Longitudinal section through a zoarium, X 12. The 

 most usual position for the calcareous plate which closes the tube would seem to be about the 

 point where the zooecial tube rises free from the zoarium. (D-F after Waters, 1884.) 



G-K. Diaperoecia rrgiilaris Mac^illivray, 1882. G. Transverse section, X 25, showing con- 

 nection through tubes divided by a disk. H. Longitudinal decalcified section, X 25. showing 

 thick membranous transverse wall. I. The thick membrane projects in the middle, but is not 

 closed below. X 85. is, tentacular sheath ; at, tissue attached to the tentacular sheaths and to the 

 zooecial wall. J. There is a thin tube (fb) arising from the transverse membrane, X 85. K. Ap- 

 pearance of the diaphragm (dp) closing the tentacular sheath. (G-K, after Waters, 190.~>. i 



L. Diaperoecia pulrhcrrima Kirkpatrick, ]SfK>. Many ovicells are reunited; they form only 

 one ovicell with many oeeiostomes (o}. (After Har-ner, 1915.) 



K*85 



