BE VISION OF SPECIES REFERRED TO GENUS BATHYURUS 
57 
This species is most closely allied to Bathyurus angelini , with 
which species I have identified poor specimens on previous occa- 
sions. With good pygidia, the spinose posterior end is sufficient 
to distinguish the species at once. 
Measurements. — The pygidium used as the holotype is 7*5 
mm. long and 8*5 mm. wide. A larger one is mm. long and 
12 mm. wide. The spine of this specimen is 2 mm. long. 
Locality. — This species was collected by the writer in strata 
near the base of the Pamelia formation (ostracod layers) in a 
small cutting on the Canadian Pacific railway at Westboro, 
near Ottawa, Ont. The holotype is No. 7821 and the paratypes 
7821 a-c. 
Bathyurus arcuatus, Billings. 
Bathyurus arcuatus, Billings, 1865. Palaeozoic Fossils of 
Canada, Vol. I, p. 205, fig. 190. 
A complete specimen of this species, which was evidently found 
after Billings y description was printed, adds to our knowledge, 
and shows that this is really a Bathyurus, allied to B. acutus and 
B. angelini. It is noteworthy for its very triangular shape, and 
the small, convex pygidium. The species has been found only 
in the famous boulder from St. Antoine de Tilly, which furnished 
so many novel species to Billings. It is probably of Beekman- 
town age. 
Bathyurus spiniger, (hall). 
Addaspis spiniger, Hall, 1847. Palaeontology New York, Yol. 
I, p, 241, PI. 64, fig. 5. 
This species is characterized by its pustulose surface and the 
long erect spine on the axial lobe of the pygidium. It is found 
in the Lowville and Black River, and possibly also in the lower 
part of the Trenton. 
Bathyurus ingalli bp. nov 
Plate VII, fig. 7. 
This last survivor of an interesting race of strictly American 
trilobites seems to be of rather frequent occurrence, though 
