Geology and Natural History. 471 



and the greater variability in the proportions of its different con- 

 stituents distinguished it from other kinds of dust collected from 

 the clouds or in the open air. The flue dust was found to contain, 

 conspicuously, lead, silver and copper ; also considerable quanti- 

 ties relatively of nickel and manganese ; further, rubidium, gal- 

 lium, indium, and thallium. The common presence of nickel 

 shows that when found in dust from the clouds it is not proof of 

 a source other than terrestrial. The authors call attention to the 

 remarkably wide distribution of gallium. It occurs in all alumin- 

 ous minerals, in many iron ores and in atmospheric and flue dust 

 from various sources ; the species bauxite contains it in larger 

 proportion than any other mineral. — Proc. Boy. Soc., Feb. 21, 

 1901. 



5. Studies in Fossil Botany ; by Dunkinfield Heney Scott. 

 Honorary Keeper of the Jodrell Laboratory, Royal Gardens, Kew, 

 533 pp., 12mo, with double page frontispiece and ]52 illustrations 

 in text. London, 1900. — In the fourteen lectures constituting 

 Professor Scott's studies the statement is abundantly sustained 

 that; "At the present day happily fossil botany is an eminently 

 progressive branch of science." These lectures are not ottered as 

 a text, but rather as a general discussion of salient and funda- 

 mental facts with a taxonomic bearing. They are limited to the 

 Pteridophytes and Gymnosperms, and even in the case of these 

 the forms from the older formations, whence the beginnings of 

 lines of descent are naturally to be expected, receive the more 

 extended treatment, the object being, in the words of Count 

 Solms-Laubach, — "to complete the natural system." 



This work is admirably suited to the general reader as well as 

 the student. No writer on the subject excels Professor Scott in 

 an easy clearness, while a particular excellence rests in his ability 

 to state simply and give with precision the work of his confreres. 

 The concluding paragraph finds a suitable place here : — " Only 

 twelve years ago it was said that iossil botany had contributed 

 little to our knowledge of the affinities of plants. Whether true 

 or not at the time it was made, such a statement would not hold 

 good now. Our whole conception of two at least of the great 

 divisions of the vegetablle kingdom — the Pteridophyta and the 

 Gymnosperms — and of their mutual relations, is already pro- 

 foundly influenced by the study of the ancient forms. Far 

 greater results may be confidently expected from further research, 

 but, by the work already accomplished, fossil botany has borne 

 no small part in the advancement of our knowledge of the affini- 

 ties of plants." This work is most earnestly recommended to the 

 attention of all interested in this subject. g. r. w. 



6. Flora of Western Middle California; by Willis Linn 

 Jepson, Ph.D. Pp. 625, 8vo. Encina Publishing Co., Berke- 

 ley, Calif., 1891. — Prof. Jepson's well-conceived and carefully 

 executed flora is a welcome addition to the literature of American 

 botany. It is the outcome of some ten years' intensive study of 

 the flora of central California, during which the author has passed 



