SPENCER NIAGARA FOSSILS. 583 



The branches of this exceedingly beautiful frond (as I have 

 only one complete specimen) appear to have occupied a semi- 

 circular position when alive, but in compression has so fallen as 

 to extend nearly in the form of a circle. Though it resembles 

 somew^hat Callo^raptus niagarensis^ yet the numerous rudi- 

 mentary branchlets and spine-like processes distinguish it from 

 that species. 



Pormation and Locality. — This species is found in the "chert- 

 beds" of the Niagara formation at Hamilton, Ontario. The 

 best specimen was obtained from Mr. Edward McLaughlin of 

 Hamilton. 



Genus Ixocaulis (Hall). 



Gr., inos, sprouts (like roots of herbs) ; kauios, a stock or stem. 



(Palaeontology of New York, vol. ii., 1852.) 



'•A plant like corneous coral, with numerous bifurcating 

 branches ; structure fibrous or plumulose." 



" The texture of this coral is similar to the Graptolites, a black 

 scaly crust or film being all that remains of the substance. From 

 the specimens examined it appears to have grown in groups, with 

 rounded or flattened stems, which are dichotomous above and 

 more or less spreading." 



This genus was described with /. pluinulosus for a type. Sub- 

 sequently Professors Hall and Whitfield published and figured 

 /. bellus in the second volume of Paleontology of Ohio, and /. 

 divaricatus in nth Report of Geology of Indiana. I described 

 /.(?) frobletnaticus (a common but poorly preserved species) in 

 the Canadian Naturalist, Dec, 1878 ; and now I venture on the 

 descriptions of /. diffusiis^ I. cervicornis^ I. ramulosus^ I. phy- 

 coides^ and /. walkeri. With regard to the species of Inocaulis 

 in my collection, the structure is shown somewhat more or less 

 perfectly in several of the species. Some of the species appear 

 to have grown in groups. In four species, at least, a central axis 

 is indicated, one of these being /. plumulosus. Prof. Hall 

 placed Inocaulis among those branching Graptolites which have 

 cellules on only one side of the stipe, owing to the inability of re- 

 cognizing the cellular structure in the American specimens. The 

 diprionidian Graptolites (or those which have a row of cells on 

 both sides) have their solid axis in a central position, as is also 



