General Notes. 
The extremities of the hairs are recurved into double hooks, as 
shown in the accompanying cut (Fig. 1). The body of the hair 
(as shown by Macloskie) is composed of two parallel, greatly- 
elongated cells, each of which is recurved, thus forming the double 
hook. In some instances I have observed septa in one or other of 
the cells, although for the most part they are wanting. The hairs 
upon each achene become interwoven with those of neighboring 
achenes, and, upon drying and twisting, they firmly bind together 
all the achenes of each head. The spreading pappus forces the mass 
to take an ellipsoid form as soon as it has escaped from the invo- 
lucer (as shown in Fig. 2), Lying 
now upon the surface of the plant, 
and entirely freed from the embrace 
of the involucer, the light mass 1s 
ready to begin its career as a min- 
iature “ tumble-weed.” After a few 
ME NSS os sze TOlls it loses most of the effet ecorolla 
Fig 2. tubes and tumbles lightly along upon 
the points of its spreading pappus. 
The jarring gradually separates the tumbling ball; but even when 
it breaks in two, each part rounds up again by the wide spreading 
of the pappus and rolls on again before the brisk breeze of the 
plains, dropping here and there an achene with its hidden seed, just 
as the great tumble-weeds, Amaranthus, Cycloloma, Corispermum, 
etc., do in their larger way.— Charles E. Bessey. 
Unperwoop’s FERNS AND THEIR ALLIES.'—This little book, 
the first and second editions of which were noted in the NATURAL- 
IST at the time of their appearance, has been entirely re-written ; 
and while the general plan of the former editions has not been 
materially modified, the details have undergone very considerable 
anges. e present edition contains thirty-four pages more 0 
matter than the last, and this increase is divided between the gen- 
eral matter (which gains nineteen pages) and the systematic portion, 
which is increased fifteen pages. 
This increase in the number of pages is due to the new matter 
introduced in the general part, consisting mainly of excellent ref- 
erences to the literature of the subject, and in the systematic part to 
a considerable increase in the number of species. The glossary 15 
also much increased in volume and value. 
The book is a most useful and handy one, and will enable the 
student of the Pteridophytes to obtain an excellent idea of their 
structure and classification. 
‘ Our Native Ferns and Their Allies, with Synoptical Descriptions = 
the American Pteridophyta north of Mexico. By Lucien M. vance 
wood, .D., Professor of Biology in Syracuse University. i 
sano, revised. New York: Henry Holt & Co., 1888. 16mo, pP- PES 
