Pe, Wh are, hig ae dang 
420 REVIEWS. 
ARRANGEMENT OF THE Faminies Or MorLusks.* — This list 
the families, orders and classes of mollusks, “prepared at the 
= of the Smithsonian Institution, for the purpose of facili- 
ing the arrangement and classification of the mollusks and 
so of the National Museum” is an exceedingly useful one, and 
pe conchologist will find it indispensable in arranging his spec- 
imen r. Gill states in the introduction, that ‘it must be 
cE i simply as a provisional list, embracing the results 
of the most recent and approved researches into the ‘systematic 
relations and anatomy of those animals, but from which, innova- 
tions and peculiar views, affecting materially the classification, 
have been excluded.” 
Those who have attempted the compilation even of a list of 
the groups of a class or higher division, know well enough the 
difficulties attending its preparation, and our author has not at- 
tempted it without giving the result of researches covering a num- 
ber of years. He is assisted in some groups by Mr. Dall. Dr. 
Gill admits the division of the mollusks into two primary grouj 
the Mollusca vera and Molluscoidea, the latter embracing the 
Brachiopoda and Polyzoa, | 
Now that several continental zoologists, among them Leuckart 
and Gegenbaur, have placed the Polyzoa among the worms, 
Prof. Morse has considered the Brachiopods as a division of A 
lids, a change alluded to by Dr. Gill, the time may come- 
these two classes will not be mentioned in conchological works: 
But as it will be long before such revolutionary views, ; 
they prove correct, will be adopted, it is most expedient in- 
an arrangement as this to let them go under the provisional 
of Molluscoidea. 
Malacologists will be interested in the remarks on the differe 
a lan, sio containing as they do many ' 
as to the general classification of the sut 
pi We trust that similar lists will be prepared by speciali 
other departments, and published by the Smithsonian Institu 
ASYMMETRY IN INsrors.t— While many of the molluses are 
examples of asymmetrical animals, as seen in the shells s as 
Arrangement of the mer of Mollusks. By Theodore Gill, M. D. Sm 
Stddtansons Collections, 227. Washington, D.C. Feb. 8, 1871. 8yo. PP: 
tOn Asymmet i tas APERAS NASD ANA, By 
8S. H. Seudder 
Burgess, the Proceedings of the Boston Society of nde History 
Svo, pp. H, with a plate, 
