584 TRANS. ST. LOUIS ACAD. SCIENCE. 



shown in four species, including the /. plufnulosus found at 

 Hamilton, Ontario. Even in most of the species that I have ob- 

 tained, the definite cell-structure is not perfectly indicated. But 

 from the fact that the axis is central, as vf\\\ be shown in the 

 description of the various species, the inference would be (even 

 where the cells are not apparent) that the stipe was characterized 

 by a row of cells on more than one side. Recently, in two spe- 

 cies 1 have observed the surfaces of the fronds marked by numer- 

 ours small pits indicating the cell-orifices situated variously all 

 around the stipe. But the texture, the general arrangements of 

 the branches, and the forms of the fronds, resemble sufficiently 

 Inocaulis plumulosus to induce me to place them along with it 

 in the same genus. 



Inocaulis plumulosus (Hall). 



Plate o, Fig-. 1. (Specimen from Hamilton.) 



(PaL-contology of New York, vol. ii.) 



"Stem flattened, dichotomous ; structure fibrous or plumulose, 

 apparently composed of imbricating elongated scales or fibres 

 which spread equally on all sides." (Hall.) 



In the specimens under consideration, all that generally re- 

 mains of the texture is the scaly crust or dark organic film, not 

 even showing the feather-like margins. But in several specimens 

 where the carbonaceous matter is removed, there is the distinct 

 imbricating scaly surface mentioned by Prof. Hall. During 

 the summer of 1880, I obtained two specimens from Col. Grant 

 which show a cellular structure. In a number of specimens I 

 observed a central axis — indicating a cellular system on both sides 

 of the stipes ; but in the specimens just referred to there are mi- 

 nute points arranged over and around the surface of the stipes 

 (the intercellular spaces being much greater than the cellular), 

 and indicating the orifices of the cellules. This latter structure 

 is shown where the corneous matter is mostly removed. 



The entire fronds are seldom found. The branches vary con- 

 siderably in size, from two to four millimetres in breadth, and 

 from six to ten millimetres in height. There are generally few 

 branches, but the fronds grew in groups and have often left con- 

 fused masses of branches on the stone. 



FormaUo7i and Locality. — This species is found at Lockport, 



