Astronomy. 415 
simple and clear to be readily followed, even without an instruc- 
tor, by any intelligent student familiar with the use of micro- 
scope. 
3. U. 8. Entomological Commission, Department of thie tae 
rior. Index volume to Dr. Riley 
makes this Index volume one of muc ue. It is intended to 
stand as the series. To increase the value of ol- 
ume, the author has brought together the tables of contentsjof 
sree of new species, added a list of descriptions of adolescent 
es, . eek oo of species not new, of food plants, and of 
‘llustrat 
- yt Fly, its ravages, habits, Senemies, and t 
i of preventing its increase, Ds: A. ACKARD, is ie 
subject of Bulletin No, 4. It is illustrated by. amap and two 
5. . S. Morse on changes in Mya and Lunatia.—Professor 
Morss has sent Ions following correction for his note on page 323 
of this volume: “A comparison of the common beach cockle 
Lunatia showed ee the present form living o n the shore to-day 
had a more depressed spire than the ancient ieven 
IV. Asrronomy. 
Theory of the Moon’s sao deduced from the pee ©} 
Univerebh radiation: by Jor nN. Sro CKWELL, 
adelphia, 1881. (J. B. Lippineott & Oule Although ie of 
e moon around the earth has been the subject of profound 
study, during the past ius hundred years, and has been the occa- 
sion of more elaborate mathematical investigations than all the 
matter of fact the latest tables of the moon scarcely represent the 
observations with greater eipic ete than those in use at the begin- 
ning of the present century. In view of this fact, the author of 
this work several years since called the attention of astronomers 
to sed great apparent errors of the lunar ry; 8 and expressed 
e 
In order to satisfy himself of the correctness of this conclusion, 
he undertook, some six years ago, a complete and systema atic 
development of the lunay theory, according to a method different 
from any that had been before applied to the problem. Th e 
