DENDROID GRAPTOLITES OF HAMILTON, ONTARIO. 



19 



Doctor Ruedemann has published the following on the species: 



It is by no means so common in our Niagara beds as one should suspect from 

 •its long bibliographic list or conclude from the direct statement of some authors 

 that it is abundant in the New Yorls rocks ; in fact, it is one of the least common 

 of the graptolites of our Rochester shale and all the references are excerpts of 

 Hall's original description. I have seen altogether not more than half a dozen 

 specimens, including Hall's types, and have not been able to find one which 

 would reveal the form of the thecie. 



Remarks. — D. retiforme is a remarkably stately graptolite, possessing wide- 

 open, funnel-shaped rhabdosomes, fragmentary specimens of which with a 

 diameter of no less than half a meter have been observed; and the size of the 

 branches and the meshwork are coarse in proportion. Pocta has compared it to 

 the Bohemian D. grande Barr[aude], also a Siluric form, and pointed out the 

 differences between the two. 



Hoiison and locality. — The two specimens here figured are from 

 the more shaly strata (beds 9-11 of section) beneath the cherty dolo- 



Fu;s. 19, 20.— DiCTYOXEMA RETIFORME IIaLL. A SMALL EHABDOSOME SHOWING THE 

 CENTRAL PORTION AND A PORTION OF A LARGER SPECIMEN. 



mite at Hamilton, Ontario. Both specimens are in the Spencer col- 

 lection. The types of the species are in the American Museum of 

 Natural History. 



DICTYONEMA CRASSIBASALE Gurley, new species. 



Plate 3, figure 1. 



Dirtj/oifcmn gracilh Spencku (not Hall), Canadian Nat., VIII. ISTS, 



p. 458 ; X. 1882, p. 165. 

 Dlctijonema gracilc Spencer, Trans. Acad. Sci. St. Louis, IV, 1884. pp. 573, 



574, pi. 2, figs. 2, 3; Bull. Mus. Univ. State Missouri, I, 1884, p. 24, 



pl. 2, figs. 2, 2a, 3. 



This abundant species has hitherto lieen identified in the Hamilton 

 collections as Dictyonema gracile Hall, but close comparison with 

 Hall's types led Doctor Gurley to propose the above new name. 



