202 BOTANICAL GAZETTE [march 



as the counterpart of "autocthonous" coals. A bog of this type 

 near Fresh Pond in Cambridge, Massachusetts, will serve as an 

 example. Samples were taken in the usual way throughout the 

 entire 30 ft. of the deposit. With the exception of the extreme 

 upper stratum, the samples present a uniformly brown plastic 

 consistency, similar to that found in open lakes. A subsequent ' 



examination revealed that the lower 28 ft. were singularly constant 

 in respect fro structure, and composed of the usual amorphous 

 material in which were imbedded pine, larch, and amentiferous 

 pollen; spores and sporangia of ferns and fungi; vast quantities 

 of diatomaceous tests and sponge spicules; minute fragments of 

 roots, stems, and leaves of the higher plants; and animal deriva- 

 tives such as insect parts, water organisms, and ejecta from aquatic 

 creatures. All of these structures are very similar to those shown 

 in figs. 1-4, with the exception of unimportant northern and southern 

 floral differences. There also appeared in this layer some indica- 

 tions of carbonized woody fragments which had been washed into 

 this former lake from a region swept by a prehistoric forest fire, 

 and there deposited. This fact is significant, since such structures 

 are of common occurrence in coal sections in juxtaposition with 

 unburned material, precluding the possibility of deposition in situ 

 (7) . These inclusions, together with the wonderfully perfect preser- 

 vation of the debris even in the very lowest strata, dispel any doubt 

 that it is of an allocthonous origin, and not one brought about by 

 an accumulation of fallen plants which later decay to a structure- 

 less mass (the " completely decomposed peat" of many writers). 



The next swamp to be considered is a so-called "Sphagnum 

 bog" in Auburn, New Hampshire. This deposit is found in depres- 

 sions between long irregular ridges, in the form of the letter Y, 

 about 2 miles in length and half a mile in breadth. In the cen- 

 tral portion there occurs a chain of more or less circular ponds sur- 

 rounded by the usual zones of growth, the inner zone of which is 

 distinctly sphagnoid. A series of tests showed a layer of lacustrine 

 peat about 27 ft. in depth. Above this and near the ponds there 

 is a floating "mat" of Sphagnum and other plants about 1 ft. 

 in thickness. Back from the shores there appears a tangled mass 

 of roots and fallen plants above this mossy stratum. Excepting 



