1917] The Ottawa Naturalist 37 



Transverse sections show that the axial region is composed of two 

 sets of tubes; the larger average 0.25 mm. in diameter and are hexa- 

 gonal to octagonal in outline; the smaller are generally between 0.1 

 and 0.15 mm. in diameter and display triangular or quadrangular 

 outlines. Peripheral region comparatively thin, less than 0.4 mm. in 

 width in a section across a branch with a diameter of 3.9 mm. 



Longitudinal sections display slightlv flexuous zooecial tubes 

 which intercept the surface quite obliquely and lack the decided cur- 

 vature commonly found in other species of the genus. Mesopores are 

 indistinguishable from the proximal portion of zooecial tubes and 

 doubtless the two had similar functions. Diaphragms numerous and 

 quite regularly spaced, crossing zooecial tubes in proximal and axial 

 regions at distances equal to from one to two times the diameter of 

 tube. Near the surface diaphragms are more numerous and generally 

 two or three of them occur in a space equal to their diameter. 



That the specimens at hand are mature individuals, even though 

 the zooecial tubes aproach the surface obliquely with little curvature 

 from axial to peripheral regions, is evident from the closer spacing of 

 the outermost two or three diaphragms in each tube as well as from the 

 thickening of the wall near the aperture. 



In comparison with H. annularis, which it resembles in the 

 angular appearance of apertures, this species i< distinguished by its 

 smaller zooecia, the generally more slender branches of the zoarium. 

 and the obliquity of the zooecial tubes. H. obliqua is probably more 

 nearly related to H. ampla and H. goodhuensis than to any other 

 described member of the genus. Its branches are on the average 

 slenderer than the smaller of those two species while its zooecia are 

 intermediate in size between them. More significant, however, is the 

 much fewer number of diaphragms in the peripheral zone of the 

 material at hand. 



Horizon and locality: Lower Trenton limestone; Wolfe Island, 

 Ontario, (Station 224). 



Class Brachiopoda. 



Order Neotremata. 



Family Trematidae. 



Genus Trematis Sharpe. 



TREMATIS sp. 



The shell thus identified is imperfectly preserved but undoubtedly 

 represents a new species of this genus. The specimen is very small, 

 about 3 mm. long and 4 mm. wide, and consists of a pedicle valve, 

 from which the apex is broken away, revealing a portion of the interior 

 of the brachial valve. The apex appears to have been much nearer the 

 posterior margin than the center of the valve. Surface markings are 

 of the T. icmbonata type and consist of radiating rows of circular pits 



