IV. Trenton Limestone Edrioasters. 1914 117 



B. The original of Plate XI. A theca lying on a small block of hard, 

 black, shaly limestone, so that only the upper face is exposed. This 

 retains the cover-plates, which, however, are crushed in. 



C. The original of Plate XIII. A theca of which the upper or 

 oral face is covered with yellowish matrix, but of which the under 

 or adapical face has been well exposed. 



In the absence of detailed information, it is assumed that these 

 specimens came from the neighbourhood of Ottawa, as did all those 

 mentioned by E. Billings. 



Mr. Walter 11. Billings lent me the following specimens of the 

 genus, and ultimately with singular generosity presented them to 

 the British Museum, under whose register numbers they are here 

 quoted. 



E 16173, a medium-sized specimen, with radius ca. 18*5 mm. 

 Adoral face disturbed and weathered, with hard black shale in the 

 hollows. Adapical face worn, and obscured in centre by hard 

 limestone matrix. Collected by W. R. Billings at Belleville, Ont., 

 on right bank of the Moira, a quarter of a mile above the railway 

 bridge (JE. lev is). 



E 16172, a smaller specimen, with radius ca. 16 mm. Most of the 

 right side is missing ; rest of adoral face fairly preserved. Adapical 

 face partly obscured by limestone and grey shale, since removed. 

 Collected by W. E. Billings at Peterborough, Ont. (PI. XIV, 

 Figs. 2, 3.) 



The British Museum has still more recently acquired — 



E 15930, a rather large individual, radius ca. 25 mm., poorly 

 preserved. Adoral face much rubbed. Adapical face coated with 

 hard black shale, now removed. From Mount Sherwood, a suburb 

 of Ottawa. W. R. Smith Collection, 1909. (PI. XIV, Fig. 1.) 



E 16054, a smaller individual, radius ca. 11 mm., preserved 

 obliquely and therefore less flattened, in a brown, sandy, calcareous 

 shale. From Belleville, Ont. W. R. Smith Collection, 1909. 



E 15900, a rather large individual, radius ca. 23 mm. Adoral face 

 fairly well preserved. Part of the adapical face exposed. Matrix 

 a dark-grey shale. From Kirkfield, Ont. Presented by Professor 

 W. A. Parks, 1909. (E. levis, Plate XII.) 



HoBIZON. 



All the known specimens are from the Trenton Limestone. 



In the absence of more precise information, I take the horizon 

 at Ottawa to be probably the limestone with shale partings which 

 Dr. P. E. Raymond (1912 x ) assigns to his Horizon 5; but it is also 

 possible that some specimens are from his lower Horizon 2, which 

 is exposed in the Hull quarries. E. Billings (1854, p. 272) found 

 " seven specimens . . . within a space of four square yards in extent, 

 and partially embedded in the surface of a stratum of limestone. 

 Along with them were" trilobites, crinoids, Amygdalocystis 

 tenuistriatus, and a quantity of Chcetetes lycoperdon. These, with 

 others, were all " in the upper one hundred feet of the Trenton 

 limestone" (p. 273). 



1 1912, Summary, Rep. Geol. Surv. Canada, 1911, p. 354. 



