1909] Jeffrey,— Nature of Algal or Boghead Coals 61 
Page 862, line 17; for A. minima (L.) Dumort. read A. MÍNIMA (L.) 
Link. 
[Arnoseris minima (L.) Link, Enum. ii. 294. (1822); 
Dumort. Fl. Belg. 63 (1827). А yoseris minima L. Sp. 
Pl. п. 809 (1753)..] 
Page 863, line 13; for L. read [Vaill.] L. 
Page 867, line3; for e. Mass. to Ind. read N. E. to Neb. (Bates). 
Page 871, line 48; for N. S. read e. Me. 
Page 872, line 36; after Ont. insert: , Wisc., 
Page 873, line 55; for Mass. read w. Me. (Miss Furbish) 
Page 888, column 2; beneath h irsuticaulis 812 insert: tanthinus 805 
| * — multiflorus 811 insert: multiformis 805 
* петогаііѕ 816 insert: nobilis 805 
column 3; beneath tennesseensis 515 insert: violaris 805 
Page 924, column 1, line 38; for Oxycoccus read Oxycoccos 
GRAY HERBARIUM. 
ON THE NATURE OF SO CALLED ALGAL OR BOGHEAD 
COALS. 
EDWARD C. JEFFREY. 
As the result of the studies of the French and Belgian paleobotan'sts 
Renault and Bertrand, on the dull bituminous coals and schists, certain 
organisms have been described, which have been considered by these 
authors to be the remains of oil-containing colonial gelatinous green 
Algae. lt is assumed that the supposed Algae owe their preservation, 
in spite of their delicate organization, to the presence of bitumen 
throughout the matrix in which they have become fossilized. The 
origin of this bituminous matter has always been a puzzling problem. 
It has been variously suggested that it is derived from the putrefaction 
of animals, through the decay of part of the algal matter, or even as a 
product of the precipitation of the dark brown humus-saturated bog 
water, in which the Algae are supposed to have existed. 
The study of coal presents a scientific problem of peculiar technical 
difficulty. On account of its black opacity, its structure can only be 
