Raymond & Narraway : Notes on Ordovician Triloeites 253 



Bumastus bellevillensis sp. nov. 

 (Plate LXI, figures 6, 7.) 



Another species of Bumastus which is very interesting in connection 

 with the preceding forms, has been found in the Trenton Limestone 

 at Belleville, Canada, by Mr. W. R. Smith. These specimens have 

 eight segments, and on first sight seemed to be the young of Bumastus 

 billingsi, but the presence of a small median pustule on the posterior 

 margin of the cephalon precludes that possibility. This characteristic 

 also separates it from any other Bumastus now known from the Ordo- 

 vician. This species differs from Bumastus milleri in its wider seg- 

 ments and more arched and incurved cephalon, two characters which 

 separate Bumastus billingsi from B. milleri. The specimens of the 

 present species are also considerably wider than are specimens of 

 Bumastus milleri of the same length. 



One of the specimens, which is exfoliated, shows a small median 

 pustule on the posterior margin of the cephalon. Another which 

 retains the test shows a small pustule over each of the lunettes formed 

 by the dorsal furrows on the cephalon. These lunettes are raised, 

 instead of depressed, as in most species of Bumastus. 



The best entire specimen in the collection is twenty-two millimeters 

 long and twenty-one millimeters wide at the genal angles. The thorax 

 is eight millimeters long, the cephalon fourteen millimeters, and the 

 pygidium thirteen millimeters. The width between the eyes is nine- 

 teen millimeters. 



The type is from the Trenton Limestone at Belleville, Canada, and 

 is in the Carnegie Museum. 



Bumastus indeterminatus (Walcott). 



(Plate LXIT, figures 8, 9.) 



Illcenus indeterminatus Walcott, 1877, Advance Sheets, Thirty-first 



Annual Report New York State Museum Natural History, p. 19. 

 Illcenus indeterminatus Walcott, 1879, Thirty-first Annual Report New 



York State Museum Natural History, p. 70. 

 Illcenus cf. /. indeterminatus Clarke, 1897, Paleontology of Minnesota, 



Vol. Ill, pt. 2, p. 716, fig. 24. 

 Cf. Illcenus indeterminatus Raymond, 1905, Annals Carnegie Museum, 



Vol. Ill, p. 347, PL 13, figs. 1, 2. 



Three imperfect cranidia of this species have been found in the 



