SPENCEK NIAGARA FOSSILS. 559 



Zoological Affinities. 



It is easily seen how difficult it was originally to recognize the 

 true character of the Graptolites. The majority of specimens is 

 represented on the stone by only carbonaceous matter, fragmentaiy 

 and structureless. It was only after examining scores of specimens 

 that one could observe such structure as has been described in the 

 following species, belonging to the Niagara formation. Equally 

 great has the difficulty been foimd in recognizing many species of 

 the Canadian Utica shale. Even the corneous structure was often 

 not unquestionably shown, though in the limestones it is some- 

 times better preserved than in the shales. But the idea of their 

 plant-origin has long since been abandoned. The solid axis and 

 the more or less jointed appearance arising from crushed cells 

 may have led to the early idea that the short fragments were 

 Orthoceratites. As before stated, Prof. Nillson was the first to 

 place them amongst polyps, and Gen. Portlock the first to class 

 them amongst the Hydrozoa with Sertularia^ in which relation 

 they are now generally regarded, as has been maintained by Prof. 

 Hall. Even if the analogy of some of the forms described be not 

 very close to the modern Sertularia^ it could scarcely be won- 

 dered at, as they all belong to only the more ancient forms of life, 

 without representatives, even in type, reaching through the long 

 geological blank. That the Niagara forms are of animal origin 

 is clearly shown, not only on account of the corneous substance 

 seen in all the species, but on account of the apparent solid axis 

 often seen, and the cellular structure sometimes seen. Even in 

 those species where the cellules are not recognizable, the analogy 

 to other specimens, when they are apparent, is sufficiently close 

 to leave no doubt. That the Graptolites belong to some form 

 of polyps, as we have stated, is generally admitted. But some 

 would place our Niagara Dictyonema and allied forms along or 

 near to Fenestella on account of some resemblance in the mode 

 of growth, but where the structure is preserved I have failed to 

 draw the analogy. 



The Structure of the Graptolites. 



The divisions proposed by Prof. Hall I have followed. First, 

 we have the radicle or initial point ; second, "the funicle or non- 

 celluliferous connecting portions of the compound fronds, and the 

 barren portion of the s-tipes"; third, the central disc. In the parts 



