84 THE GEOLOGICAL HISTORY OF PLANTS. 



em Barramunda or Ceratodus of Australia, and with 

 teeth suited for grinding vegetable food. It is also possi- 

 ble that some of the smaller plate-covered fishes (Placo- 

 ganoids, like PtericUhys) might have fed on vegetable 

 matter, and, in any case, if they fed on lower animals, the 

 latter must have subsisted on plants. I mention these 

 facts to show that the superabundant vegetation of this 

 age, whether aquatic or terrestrial, was not wholly useless 

 to animals. It is quite likely, also, that we have yet 

 much to learn of the animal life of the Erian swamps and 

 woods. 



NOTES TO CHAPTER III. 



I. — Classification of Sporangites. 



It is, of course, very unsatisfactory to give names to mere frag- 

 ments of plants, yet it seems very desirable to have some means of 

 arranging them. With respect to the organisms described above, 

 vfhich vrere originally called by me Sporangitea, under the sup- 

 position that they vrere Sporangia rather than spores, this name 

 has so far been vindicated by the discovery of the spore-cases belong- 

 ing to them, so that I think it may still be retained as a provisional 

 name ; but I would designate the whole as ProtosalvinicR, meaning 

 thereby plants with rhizocarpean affinities, though possibly when 

 better understood belonging to different genera. We may under 

 these names speak of their detached discs as macrospores and of 

 their cellular envelopes as sporocarps. The following may be recog- 

 nized as distinct forms : 



1. Protosalvinia Muronensis, Dawson, Syn., Sporangiies Huron- 

 ensis, " Report on Brian Flora of Canada," 1871. — Macrospores, in 

 the form of discs or globes, smooth and thick-walled, the walls pene- 

 trated by minute radiating pores. Diameter about one one-hun- 

 dredth of an inch, or a little more. When in situ several macro- 

 spores are contained in a thin cellular sporooarp, probably globular 

 in form. Prom the Upper Erian, and perhaps Lower Carboniferous 

 shales of Kettle Point, Lake Huron, of various places in the State of 

 Ohio, and in the shale boulders of the boulder clay of Chicago and 

 vicinity. First collected at Kettle Point by Sir W. E. Logan, and 



