

LIBRAR 



THE OTTAWA f^ATURALIST. 



Vol. XVIII. OTTAWA, SEPTEMBER, 1904. No. 6 



DESCRIPTION OF A NEW GENUS AND SPECIES OF 



RUGOSE CORALS FROM THE SILURIAN 



ROCKS OF MANITOBA. 



By J. F. Whiteaves. 

 Aphyllostvlus, gen. nov. 



Corallum consisting' of slender, contiguous, subcylindrical 

 corallites, that are circular or nearly circular in transverse section, 

 and th'dt seem to have formed part of a compound, branched, 

 fasciculate, ascending and somewhat spreading colony, essentially 

 as in Pycnostyhis. Surface markings of the exterior of the co- 

 rallites unknown. 



The structure of the interior of the corallites consists of con- 

 spicuous transverse tabula, and of numerous, very minute, spini- 

 form septa. The tabulte, though irregular in their disposition and 

 in their distances apart, are for the most part complete and 

 continuous. The spiniform septa consist of both longitudinal and 

 transverse rows of close-set, very short, straight and inwardly 

 directed, minute spinules, not very unlike those of a Silurian 

 Favosite, but much smaller and shorter. Where the tabulae are 

 comparatively far apart, the longitudinal arrangement of the rows 

 of spinules is very obvious, and there are from four to seven 

 spinules in each longitudinal row, between two of the tabulae. 

 But, in places where the tabulae are close together, the transverse 

 arrangement of the rows of spinules is more apparent, and there 

 are either one or two transverse rows of spinules between two 

 tabulte. 



