90 The Ottawa Naturalist. [November 



theca is 65 millimeters in height, the length of the column is 108 

 millimeters, its width near its attachment to the theca is 7 millimeters, 

 at mid-length this width is nearer 5 millimeters, toward the base of the 

 column it increases to 6 millimeters, and then, within a distance of 3 

 millimeters, the column widens rapidly into a circular attachment disk, 

 about 17 millimeters in diameter. The upper surface of this attach- 

 ment disk is convex, and the lower surface is sufficiently concave to 

 suggest attachment to a more or less convex object. The outlines of 

 this attachment disk probably were irregularly circular, certain parts 

 extending farther than others from the center. There is no differen- 

 tiation in size or form between the columnals along the middle third 

 of the stem compared with the columnals toward either end. All are 

 very thin and of approximately the same lateral diameter. During 

 the growth of the stem the columnals probably were added at the top. 

 The stem evidently was sufficiently strong to support the theca in a 

 more or less erect position. 



19. Geological horizon and geographical distribution. Com- 

 arocystites punctatus Billings is known chieriy from the Trenton, in 

 the vicinity of Ottawa, in Canada. Professor Percy E. Raymond, who 

 has made a special study of the Ottawa area (Guide Book No. 3, 

 International Geological Congress, 1913, p. 151), cites Comarocystites 

 punctatus only from the quarry located in the angle between the two 

 railroads, several hundred yards north of Walter's Axe Factory quarry, 

 in Hull, a town on the opposite side of the river from Ottawa, north- 

 westward. Here it occurs in the Crinoid zone, associated with 

 Edrioaster bigsbyi, Cyclocystoides halli, Isotelus latus, and Amphili- 

 chas cucullus. The strata in this quarry consist of rather thick- 

 bedded, coarse-grained, gray limestone, separated by black shale 

 partings in which most of the fossils are found. The writer found two 

 specimens of Comarocystites on the surface of the highest layer of 

 massive limestone exposed in the Robillard quarry, three miles east of 

 Ottawa, on the south side of the Montreal road. This massive lime- 

 stone is referred by Raymond to the Tetradium zone, and belongs 

 above the Crinoid zone. The top of the Tetradium zone is exposed 

 also in the quarry immediately behind the axe factory, in Hull. In 

 the overlying Prasopora zone Mr. James E. Narraway found several 

 specimens of Comarocystites. Several small specimens were found by 

 Mr. Narraway in the lower part of the Cystid zone exposures at 

 Nepean Point, within a short distance of the horizon at which 

 Agelacrinites inconditus is fairly common. This part of Cystid zone 

 is probably not far above the top of the Prasopora zone. The well 

 preserved theca illustrated by figure 1 on plate II of the present com- 

 munication was found by Mr. Narraway, in the quarry at the north- 

 east corner of Bell Street and Carling Avenue, immediately east of the 

 railway leading into the lumber yard east of Dow lake. Here 



