NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
541 
Fig. 159. — Anatomical structure of tlie family Tubucellariidae Busk, 1884. 
A-D. Tubucellaria cereoides Ellis and Solander var. chuakerisis Waters, 1907. A. Section 
through two ordinary polypides and two peristomial ovicells. This is an absolute copy of one 
section, thougli 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withdrawn from the opening, but this may only be the result of decalcification and preparation 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 peristomial ovicell containing a larva (I). The diminutive polypide is shown and the 
plug (pi) 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 (ov) is immediately below the diminutive 
polypide, and there are parenchym threads (mesenchyme) 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 85. C. Section showing the diaphragm (d) retracted; op, operculum; ts, tentacular 
sheath; rs, septulae; p, polypide folded in the zooecium ; X 85. D. Transverse section showing 
compensatrix, X 85. (A-D after Waters, 1907.) 
E. Tubucellaria opuntioides Pallas, 1766. Longitudinal section of a zoarium, X 25, intro- 
duced to show terminology. (After Levinsen, 1909.) 
