DENDROID GRAPTOLTTES OF HAMILTON, ONTARIO. 9 



Doctor Spencer's description is as follows: 



Frond moderately flabelliform. The base of the frond arises from a single 

 stipe, and from near its summit most of the branches originate and moderately 

 diverge above, vs^ith few bifurcations. The texture is corneous, with the surface 

 strongly striated. The cellules are arranged along one of the margins of the 

 branches, and have angular openings, processes, or cell denticles, marking 

 these openings as in figure So, which is a branch enlarged. 



The largest frond is 4 cm. high, exclusive of the basal stipe, of which the 

 length of a centimeter is preserved. It expands above in straight radiating 

 branches until the summit is rather more than 3 cm. across. The not-very- 

 numerous branches are comparatively stout, being about a millimeter broad. 

 The branches occasionally touch or overlap, but this arises from the manner in 

 which they were compressed in the rock. This species is easily distinguished 

 from any other of the group that is obtained at Hamilton. 



Formation and locality. — This fossil is found in the more shaly dolomites 

 below the "Chert beds" of the Niagara formation, at the "Jolly-cut road," 

 Hamilton, Ontario. 



This species is represented by two specimens in the Spencer collec- 

 tion, one of which has been photographed and figured by Doctor 

 Giirley. (Text fig. 9 and PL 1, fig. 3.) According to this figure, 

 the width of the branches is usually 0.8 mm., not infrequently reach- 

 ing 1 mm. ; a few as narrow as 0.6 mm. The branches are set about 

 17 to 20 in 25 mm. of width. 



DENDROGRAPTUS PRAEGRACILIS Spencer. 

 Text figures 4, lo. Plate 2, figure .3. 



Dcndrograptus praegracili-fi Spencer, Can. Nat., X, 1882, p. 165, nomen 

 nudum; Trans. Acad. Sci. St. Louis, IV, 1884, pp. 564, 569, pi. 1, fig. 7; 

 Bull. Mus. Univ. State Missouri, 1, 1884, pp. 14. 19, pi. 1, fig. 7.— Miller, 

 North Amer. Geol. and Pal., 1889, 

 p. 185. — GuRLEY, Journ. Geol., lY, 

 1896, pp. 95, 308. 



The original description is as follows : 



Frond diffuse. The branches, few in num- 

 ber (three or four), originating from a long 

 slender stipe, with each sending off smaller, 

 very slender branchlets. Surface striated, 

 and celluliferous on one side. Branches 

 about a quarter of a millimeter broad and 

 diverging considerably. The umbelliferous 

 summit is about as broad as high (measuring 

 I5 cm., besides the long stipe). 



The mode of branching and general appearance of this fossil closely resem- 

 bles D. gracilis of the Quebec group, only it is much smaller. 



Formation and locality. — It occurs in the Niagara dolomite at Hamilton, 

 Ontario. 



A single specimen (text fig. 10. and PL 2, fig. 3), from the Niagara 

 chertv dolomite at Hamilton, Ontario, occurs in the U. S. National 



Figs, lu-11. — 10, Dexdrograptus 



PRAEGRACILIS SpENCEK (SEE ALSO 



Pl. 2, FIG. ;i) ; 11, Dexdrograp- 

 tds phainotheca, new species. 

 View of the type - specimen. 

 (See also I'l. 2, fig. 2.) 



