348 
POPULAR SCIENCE REVIEW. 
on this side of the Atlantic are cited and discussed, where necessary, in great 
detail. Taken in conjunction with the beautiful series of forty-eight coloured 
plates with which the descriptions are illustrated ; this portion of the work, 
as a means of distinguishing the organisms, and as a 1 recreation of the eye/ as 
old Knorr has it, leaves little to he desired. But we cannot help thinking that 
the author would have done better, and have given his work a far higher value, 
had he taken a rather more philosophical view of what is wanted in the shape 
of genera and species in the classification of these lowly organisms. The multi- 
plication of generic names especially is a continual stumbling-block to everyone 
but the mere specialist ; and when we examine the beautiful figures here given 
and compare them with the observations and figures of Dr. Wallich (Ann. 
Mag. Nat. Hist. 1864), one is driven perforce to accept the views of the latter 
distinguished observer, and to hold that, for the purposes of science, the esta- 
blishment of species and genera upon slight variations in the form and structure 
of little cases like those of the Difflugice and Fuglyphce, is worse than useless. 
Nay, Prof. Leidy himself evidently holds a very similar opinion, for he cites 
the authority of such observers as Carpenter, Williamson, Wallich, Brady, 
Parker, and Jones to show 1 that the members of the class are infinitely vari- 
able, and that indeed no absolute distinctions of species and genera exist, such 
as appear more definitely to characterize the higher forms of animal life/ 
He adds : 1 My own investigations rather confirm this view, and, under the 
circumstances, we can hardly regard the more conspicuous and prevailing 
forms as so many nominal species, in likeness with the species of higher 
organic forms, more or less intimately related, and by intermediate forms, or 
varieties, merging into one another’ (p. 6). This seems very nearly to ex-* 
press the state of the case ; but because there are no well-marked or easily 
distinguishable groups, it by no means follows that it is of no consequence 
how many groups we adopt. 
In these remarks we have no wish to detract from the value of Prof. 
Leidy’s magnificent work, which is not only a splendid monument of much 
labour carefully and intelligently performed, but also a most important and 
indispensable book for the investigator of the lowest forms of animals. We 
congratulate him heartily on its completion, and on the exceedingly satis- 
factory manner in which it has been produced. 
METEOKOLOGY.* 
There has lately been an addition to the Literature of Meteorology in 
the shape of two pamphlets, each of which merits some notice. The first 
issued officially by the Meteorological Office is entitiled Aids to the Study and 
Forecast of Weather ; and the second by E. J. Lowe, F.R.S., is called The Com- 
ing Dr ought, or the Cycle of the Seasons, with a Chronological History of all the 
* Aids to the Study and Forecast of Weather. By W. Clement Ley, M. A. 
8vo. London : Bemrose & Sons. 1880. 
The Coming Drought , or the Cycle of the Seasons. By E. J. Lowe, 
F.Pt.S. 8vo. London : Bemrose & Sons. 1880. 
