BOTANICAL GAZETTE. 101 



that "in certain groups absolute or practical definition of the 

 species by written characters or descriptions is beyond my powers." 

 The greatest confusion seems to have arisen from the fact that 

 many old species were established upon cultivated plants and others 

 upon a perfect medley of forms, which being resolved leaves nothing 

 behind upon which to establish a species and a name must be 

 suppressed. For instance, Aster Novi-Belgii, L., disappears, being 

 swallowed up completely by neighboring species; which is also the 

 case with A. miser, L., and A. Tradescanti, L., although in this 

 last case the old name claims a small share, the rest all disappear- 

 ing under A. paniculatus Lam., and A. vimineus, Lam. The name 

 A. linifolius subsides from the American Flora, and so it goes, until 

 in the forthcoming work on Compositce it will take us many a day 

 to get the run of our Asters. 



As for $olidago, which now numbers nearly 80 species in North 

 America, Dr. Gray gives a general arrangement under the three 

 sections Viegaurea (which is made to include the old Chrysas- 

 trum), Euthamia, and Chrysoma. Under the first section the 

 species are arranged in five groups, Squarrosce (§ Chrysastrum, 

 T. & G.), Glomendijiorai, Thyvsiflorce, Paniculata\ and Corymbosce. 

 But few of the changes can be noted. For example, S. thyrsoidea, 

 E. Meyer, becomes 8. macrophylla, Pursh; the vars. multiradiata 

 and humilis of S. Virgaureaaxe acknowledged as species ; S.virga- 

 ta, Mx., falls under S. stricta, Ait.; the 8 altissima of the Manual 

 is S. nigosa, Mill., 8. Muhlenbergii, T. & GL comes under S. arga- 

 ta, Ait.; and S. gig.mtea is but a variety of S. serotina. 



In the same contribution are the descriptions of many new 

 species, mainly from Arizona and adjacent districts. A new 

 buckeye from Lower California is an interesting discovery and many 

 well-known genera receive large additions. A synopsis of North 

 American species of Baccharis (18 in number) is given. Three new 

 genera are described, all Compositce', Plxmmera, from Southern Ari- 

 zona, related to Actinella and named in honor of Mrs. J. E. 

 Lemmon; Dugesia, from Northern Mexico and dedicated to Prof. 

 Alfred Duges, a Mexican Zoologist; and Hecastocleis, from Nevada, 

 a member of the Mutisiacece, and whose generic name alludes to 

 the separate enclosure of each flower in its involucre. 



A footnote informs us that the unequal insertion of the 

 stamens will no longer serve to distinguish Collomia from Gilia 

 and that hence Nuttall's Collomia must be remanded to the already 

 large genus Gilia. — J. M. C. 



Contributions to American Botany, by Sereno Watson; 

 Proc. Am. Acad., Vol. XVII. — The larger part of this contribution 

 is devoted to a list of the Polypetalcn from S. W. Texas and N. 

 Mexico, collected chiefly by Dr. E. Palmer in 1879-80. The list is 



