REPORT OF THE DIRECTOR I9IO 



247 



Genus PALAEOCYSTITES Billings 

 Can. Org. Rem. Dec. Ill, p. 68-69 



Palaeocystites dawsoni Billings 

 Can. Org. Rem. Dec. Ill, p. 70-71 



As this species has some valuable evidence to offer concerning the 

 question of respiration and as it allows the cystids to be better 

 represented in our discussion, we will give it a somewhat detailed 

 description and admit its testimony. 



Sice, form, etc. The more perfect specimen of the two syn- 

 types in the collection of the Geological Survey of Canada at Ottawa 

 is 18 mm long and about lo mm in greatest width. 

 The upper half is somewhat cylindrical with a .hemispherical top, 

 the lower half is obconic and tapers very regularly to a diameter of 

 2.5 mm. This specimen is illustrated by text figure 21 and is 

 here designated as Syntype A. The following quotation from Bill- 

 ings's description is evidently a reference to it: " The largest speci- 

 men collected is a fragment of the 

 lower half and indicates that the 

 length of the body was about one 

 inch, its greatest diameter being half 

 an inch." It should be noted that, 

 while Billings called this syntype '' a 

 fragment of the lower half," yet he 

 found it complete enough to enable 

 him to determine the length of the 

 species. As he left it, no portion of 

 the orad end was visible, it being 

 heavily covered by a colony of bry- 

 ozoa, and the side uppermost in the 

 bed had but one plate sufficiently 

 weathered to remove a portion of its 

 surface (see fig. 30). Removal of 

 the incrustation for some distance pio. 21 Paiacocvstites dawsoni 



around this seems to show that we BUI. Syntype a. .X3. Scaleinmm 



are dealing with a nearly complete specimen and one in which the 

 epithecal canal coverings were well preserved. The specimen has 

 the crystalline calcite of its plates broken and shattered on one 

 side, caused by its removal from its bed, and a piece broken 

 from its opposite side which was afterward replaced. These in- 



