47 
Dianulites rocklandensis n. sp. 
Plate II, figures 1, 2 
Large, irregular branches measuring about 7 mm. in 
diameter. 
Internal Characteristics . The walls of the tubes have a 
pronounced granular structure. A vertical section shows that 
they are somewhat crenulated especially at the initial stage of 
the young tubes which expand very rapidly. Diaphragms 
wanting in the axial region but present in the peripheral region 
being from half their width to their width apart. A tangential 
section emphasizes the granular structure of the walls. The 
tubes are polygonal, partly separated from one another by 
angular mesopores. The mesopores are so variable in size that 
it is sometimes difficult to distinguish the larger ones from the 
true zooecia. 
D. rocklandensis differs from the only other known American 
species in its ramose growth, in having few diaphragms and 
smaller tubes. It averages about five tubes in 2 mm. more 
nearly than four. It resembles the Russian species D.fastigiatus 
in the variability of the size and shape of its mesopores, but 
differs from it in its general shape and in its diaphragm system. 
Formation and Locality. The Leray beds of the Black 
River and the Rockland beds of the Trenton at Rockland, Ont. 
Nicholsonella ottawaensis n. sp. 
Plate II, figures 3, 4 
Zoarium, irregular, flattened mass. The complete colony 
was not found. The surface is too worn to preserve its character- 
istics. 
Internal Characteristics. A tangential section shows large 
zooecia averaging from three to four in 1 mm. Near the surface 
the apertures are round and completely isolated, the interspaces 
being occupied by prominent tubuli, the larger ones of which 
have their origin in the older region where they are exhibited as 
19856-4 
