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ing the purely descriptive portions of the volume and occupying the first 137 

 pages is a series of chapters dealing with the relationships of the Hepaticae to 

 other plants, the general characteristics of the group, their structure, their 

 biology, and the various systems of classification which have been proposed. 

 The descriptions are unusually full and clear, and keys for the determination 

 of specimens are everywhere inserted. Practically every species occurring 

 within the assigned limits of the work is figured in more or less detail, and the 

 majority of the illustrations are from original drawings, either by the author 

 himself or by P. Janzen. 



When the great similarity between the hepatic flora of Europe and that of 

 North America is remembered, it will be seen at once that the present publi- 

 cation is of the utmost importance to students on this side of the Atlantic. The 

 first volume includes descriptions of nearly 250 species; considerably more than 

 half of these are already known from North America, and it is probable that a 

 good many of the others still await discovery. 



The genera recognized and the names applied to them are for the most part 

 familiar to American students. It should be noted, however, that the generic 

 names of S. F. Gray are not accepted, Pallavicinia appearing as Blyttia and 

 Moerckia, Riccardia as Aneura, Nardia as Alicularia and Eucalyx, and Mylia as 

 Leptoscyphus. One generic name which is open to criticism is Haplozia, in 

 spite of the fact that many other writers are showing a tendency to use it. As 

 defined by the author Haplozia is essentially the equivalent of Jungermannia, 

 as restricted by Howe in his "Hepaticae and AnthocerOtes of California." The 

 name is due to Dumortier who, however, spelled it ^' Aplozia.'^ He originally 

 applied it in his "Sylloge Jungermannidearum " of 1831 to a subgenus under 

 Jungermannia, and it was not formally published as a genus until 1874, when 

 he issued his "Hepaticae Europae. " In its subgeneric sense Aplozia contained 

 fifteen species, which recent writers distribute among the genera Mylia, Jame- 

 soniella, Jungermannia, and Nardia. In its original generic sense it contained 

 twenty-three representatives of the same genera and also two members of the 

 genus Southbya. It is evident, therefore, that Aplozia cannot be recognized as 

 a modern genus without extensive restrictions and emendations, and the diffi- 

 culty is increased by the fact that Dumortier indicated no definite species as a 

 generic type. Meanwhile, in 1845, Nees von Esenbeck published in the "Synop- 

 sis Hepaticarum" the monotypic genus Liochlaena, based on Jungermannia lan- 

 ceolata, a species which Dumortier and all subsequent writers who accept Aplozia 

 include under this genus. According to the Vienna Rules, Liochlaena has a dis- 

 tinct right of priority over Aplozia and ought to be adopted if authors agree that 

 Jungermannia must be given up altogether as a generic name. 



With respect to the definition of species Dr. M tiller occupies a somewhat 

 conservative position. Although he recognizes a large proportion of the species 

 accepted by Lindberg, Schiffner, and other writers, he looks upon many of them 

 as mere variations, due to unusual external conditions. Such species he either 

 reduces directly to synonymy or describes as varieties or forms. He is further 

 careful to distinguish undoubted species from those which he designates "kleine 

 Arten," which expresses about the same meaning as the "elementary species" 



