ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 275 



structure of which has been preserved. Corynepteris dates from I860, 

 Zygopteris from 1845. Zeiller has insisted on the evident analogies 

 between the two genera, in respect of both fructification and sterile 

 frond. But there still remained the necessity to discover some clear 

 obvious morphological character applicable to impressions and fossils 

 alike. Such a character Bertrand discovered in a specimen of Corynep- 

 teris coralloides from Bruay, where the rachises of the two pinnee are 

 inserted at the same point on the primary rachis and are coalescent for 

 about 0*5 cm. In other specimens from Lens the same structure was 

 found, and it corresponds with what has been described for Zygopteris. 



Tree-ferns of North America.* — W. R. Maxon gives an account of 

 the tree-ferns or North America, discussing the distribution and habitat, 

 the dimensions and shape of trunk, resting periods, variability in rate 

 of growth, branching of trunks, use as timber, characters of the leaves 

 of Cyathea! and Dicksoniese, characters used in the classification of 

 Cyathea, Hemitelia, Alsophila, Dicksonia, Culcita, Gibotium. Excellent 

 distinguishing characters are afforded by the trunk and by the vascular 

 parts of the frond, especially by the base of the stipes, which is usually 

 armed with spines, or clothed with scales, characteristic for the several 

 species. Yet these are the very parts usually missing in herbaria, the 

 whole material consisting of but a portion of the lamina, or it may be 

 a single pinna. Hence, the study of the group is very difficult. Within 

 recent years, however, fuller data have been obtained from collections 

 made by specialists. Sections of the trunks, stipes, lower, middle and 

 upper pinna? of the fronds of most species are now available for study. 

 Excellent photographs of habit, detail, etc. are supplied. 



Tropical American Ferns. — W. R. Maxonj publishes further 

 studies of tropical American ferns. In No. 4 he gives an account of 

 19 species of the Asplenium Trichomanes group, with a key and figures 

 of sori, scales, etc. ; 4 species of Dicksonia ; 10 species of Odontosoria ; 

 Bommeria (4) and allied genera, such as Hemionitis and Gymnopteris ; 

 5 new species of Lycopodium ; and a new Cyathea. 



In No. 5 are the following: 11 species of Oleandra; Polypodium 

 duale and its allies; 6 new species of Polypodium-, Pellsea Arsenii; 

 Psilogramme ; Hemitelia (10) ; Marattia (2) ; Lycopodium (10). Diag- 

 noses of several new species are included as well as keys, plates, and 

 figures. 



M. SlossonJ describes Trichomanes rhipidophyllum and Polystklnim 

 machserophyllum, two new ferns from tropical America, giving figures of 

 their structure. 



* Smithsonian Eeport for 1911 (Washington, 1912) pp. 463-91 (15 pis.), 

 t Contrib. U.S. Nat. Herb. Washington, xvii. (1913) pp. i-x, 133-79 : pp. i-x, 

 391-425 (23 pis. and figs.). 



t Bull. Torrey Bot. Club, xl. (19131 pp. 687-90 (1 pi. and 1 fig.). 



