96 
Muhl., is C. arisiattis, Rottb., a change already noted by Mr. Watson 
in the Botany of California. C, rotundtes, L., a species of tropical dis- 
tribution, includes var. Hydra, Gray, Manual, C esculenius^ L., is 
the older name for C, phymatodes, Muhl.^ and C. Hennanni^ Buckley, 
(var. Hermanni, Watson) is included by Mr. Clarke. C. Grayii^ 
Torr., is referred to C. setif alius, Torr., we suppose an older manu- 
script name, having found no such published description of the plant, 
Desmids of 
setif alius oi C filiculmis. — N. L. Britton. 
?/ Pediastrums; with i,ioo 
Illusiratio7is on %i^ colored Plates. By Rev. Francis Wolle 
pp. 1 68. Bethlehem, Pa. 1884. 
Although we have never specially studied the subject of fresh- 
water algoe, we have more than once had occasion to consult the 
pages of Rabenhorst to ascertain the name of some beautiful desmid 
which we have observed floating in tlie field of the microscope, and we 
know from so slight an experience as this how difficult it is to iden- 
tify these minute plants without the aid of accurate figures. Those 
many readers of the Bulletin who have, during the last few years, 
turned their attention to the study of these low forms of vegetable life, 
will heartily thank Mr. Wolle for placing at their disposal a work in 
which all obstacles of this nature are removed through the eleven 
hundred colored figures which he has given them, and which illus- 
trate all the species and varieties that are described in the text. 
The desmids, the group of fresh water algae to which this work is 
specially devoted, embrace a large number of species, some of them 
of most exquisite forms, and the publication of a work like the one 
under consideration must certainly have the effect of giving a further 
impetus to the study of them among those who have a microscope 
at their command, and who desire to know more about the inhabi- 
tants of the unseen world. 
As regards paper and letter-press the book is handsomely got up, 
the illustrations are beautifully drawn and colored, and we scarcely 
see how the author is able to offer the work to students at so low a 
price as five dollars. 
Vacation Cruising in the Chesapeake and Delaware Bays, By J. T. 
Rothrock, M.D., Professor of Botany in the University of Penn- 
sylvania. Philadelphia: J. B. Lippincott & Co., 1884. 
It is rather late in the season to allude to this charming little book 
by a botanist whose name is familiar to all our readers, but it is none 
too late to recommend the perusal of it to those who, before many 
months elapse, will be laying plans for next year's vacation, and who, 
like our author, may have the means at their command to spend it 
upon the water, and in their own craft. But in making these remarks 
we do not mean that the reading of the book should be restricted to 
the class that we have just mentioned, for it is very pleasantly written, 
full of instruction, and will prove equally interesting to all those 
whose destiny compels them to while away their vacation hours upon 
dry land. 
Correction —On page 64, line 17, read Fig. A is a node, / is a 
petiole scar. 
