NORTH AMERICAN EARLY TERTIARY BRYOZOA. 541 



FIG. 159. Anatomical structure of the family Tubucellariidae Busk, 1884. 



A-D. TubucelJaria cereoides Ellis and Solander var. clntakensis Waters, 1907. A. Section 

 through two ordinary polypides and two peristoruial ovicells. This is an absolute copy of one 

 section, though in two or three cases where the operculum had not been well cut through that 

 detail had to be taken from the following section. In the peristomial ovicell the plug is seen 

 withdrawn from the opening, but this may only be the result of decalciflcation and preparation 

 as changes are sure to take place when the calcareous support is removed. The operculum (op) 

 has opened the peristomial ovicell for the passage of the diminutive polypide. and the position 

 of the tentacular sheath (ts) and diaphragm (d) can be followed. In this case there is no 

 larva in the ovicell, but apparently there has been one and the ovaria (ov) would "probably soon 

 furnish others. The parenchym passing through the rosette plate is seen at rp; X 85. B. Sec- 

 tion of the poristoniial ovicell containing a larva (I). The diminutive polypide is shown and the 

 plug (;*/) to close the opening; also the remains of the rectum (r) and the encysting portions of 

 the digestive tube (dt) are cut through. The ovarium (or) is immediately below the diminutive 

 polypide, and there are parenchym threads (niesenchyme) from it to one of the cysts. This 

 apparently shows an earlier stage than fig. A, as we still have the indications of the complete 

 polypide; X So. C. Section showing the diaphragm (d) retracted; op, operculum; ts. tentacular 

 sheath: rs, septulae; /), polypide folded in the zooecium; X 85. D. Transverse section showing 

 compensatrix, X 85. (A-D after Waters, 1007.) 



E. Tulucellaria opuntioidcs Pallas, 1706. Longitudinal section of a zoarium. X 25, intro- 

 duced to show terminology. (After Levinsen, 1909.) 



