256 The Ottawa Naturalist. [March 



wards. In external characters it resembles A exilis, but the 

 much greater development of the septa distinguishes it there- 

 from." 



This species is regarded as belonging to the genus Zaphrentis 

 on account of its well developed septa : it appears to differ from 

 Z. gigantea, Lesueur principally m being more slender, in having 

 fewer septa and also in being typically more strongly annulated. 

 In the type specimen a longitudinal section through the cup 

 shews complete, slightly concave tabulse stretching across the 

 visceral chamber from wall to wall and abruptly turned down 

 at their edges. 



Z. invenusta, Z. Egeria, and Z. subrecta are believed to be 

 identical with Z. uiirabilis.-Axxdi to the same species are assigned 

 a number of specimens in the collection that possess the slender 

 form and the comparatively few septa that are characteristic of 

 the species. 



Using the type specimen as a basis Z. mirabilis may be 

 described as follows — 



Corallum simple, long, cylindrical, slender, pointed at the 

 base, generally curved or variously twisted, ending above in a 

 moderately deep cup with thin vertical side walls and a flat or 

 slightly undulating bottom ; reaching a length of 30 cent, or more 

 and apparently not exceeding between four and five cent, in dia- 

 meter. Septa of two sizes, alternating, the primaries somewhat 

 flexuous, reaching generally rather mo e than half way to the 

 centre, the secondaries somewhat variable in their length being 

 in different specimens from less than one-third to about three- 

 fourths as long as the primaries ; numbering in all from about 

 sixty to one hundred. On the surface of the corallum the posi- 

 tion of the outer ends of the septa is indicated by distinct, 

 shallow, longitudinal furrows. Tabular complete, numerous, flat 

 or undulating, turned down at their edges. A small septal fovea 

 is generally discernable near the lateral margin to one side of 

 the convex curve. 



Locality and formation, — Corniferous formation of Ontario. 



