20 GEOLOGICAL AND NATURAL HISTORY SURVEY OF CANADA, 



IlETEROTRYrA, Nicholsoii, (Kcstriclod.) 



*'Zoarium frondcscent, rarely incrusting. Tubes prismatic. Inter- 

 stitial cells developed in moderate numbers, sometimes collected into 

 ' maculo?,' Spiniform tubuli small, more or less numerous. No cystoid 

 diaphragms." Trenton and Cincinnati. (E. 0. Ulrich, Journ. Cincinnati 

 Soc. Nat. nist., Vol. y., p. 155, 18S2.) 



Since the above was written Mr. Ulrich has published a more detailed 

 description of the genus, which is here subjoined : — 



"Zoarium growing from an expanded base, attached to foreign objects, 

 upward into simple, often undulated or irregularly inosculated fronds, and 

 occasionally into flattened branches. Cell-apertures varying in shape 

 from polj^gonal to circular. They are separated from each other by walls 

 or interspaces, which may be comparatively thin (^H, soUtaria, Ulrich), or 

 nearly as thick as their own diameter (//, Vaupeli, Ulrich). Interstitial 

 cells from few to very numerous, always angular or sub-angular. Spini- 

 form tubuli small, usually numerous (sometimes excessively so, as in II. 

 Vaupeli), occasionally inflecting the walls, and giving the cell-apertures 

 an irregularly petaloid appearance. Internally wo find that the walls of 

 the tubes are more or less thickened as they enter the * mature * region, 

 and apparently amalgamated with one another. The diaphragms are 

 straight, of one kind only, more numerous in the interstitial tubes than in 

 the proper zoa}cia, and always more crowded in the ' mature ' regions 

 than in the ' immature ' or axial regions." (E. O. Ulrich, Journ. Cincin- 

 nati Soc. Nat. Hist., Vol. VI., p. 85, 1883.) 



Heterotrypa solitaria, Ulrich. 



Heieroirypa solitaria, Ulrich, Journ. Cincinnati Soc. Nat. Hist., Vol. VI., p. 8S, 

 plate I., figs. 3, 3a, 3b, 1883. 

 A basal expansion of this species. 



Locality and Formation. — Ottawa City. Trenton Formation. 

 Collector.— ^Ya\tov R. Billings. 



Spatiopora, Ulrich . 



" Incrusting, and forming very thin, largo expansions, with a smooth 

 or strongly tuberculated surface. Cells shallow, with oblong or irregular 

 apertures. Interstitial cells sparingly developed. Spiniform tubuli 

 generally of considerable size." Trenton and Cincinnati. (E. O. Ulrich, 

 Journ. Cincinnati Soc. Nat. Hist, Vol. V., p. 155, 188?.) 



