712 The American Naturalist. [Augnst, 
atrophied at an earlier stage in the development. This manner of 
development, though peculiar, corresponds fundamentally to the Mol- 
luscan type. The renal ducts probably originally served as sexual 
ducts also (e. g. Chiton). In Paludina we have, associated with the 
twisting of the body, a differentiation in function, by which the right 
uro-genital duct comes to serve simply as a renal organ and the left — 
as a sexual organ. 
Among the most valuable features of this paper is the review of the 
literature of the subject. The author’s discussion of the relationship 
of the Mollusca to the annelids and flat worms is not so important. 
Many points in the paper and some whole sections (e. g. the develop- 
ment of the sense organs) have been passed over in this brief review. 
I trust, however, that reference has been made to the points of special 
interest, and such points are not few. The author’s clearness and con- 
ciseness of statement make his paper a very readable one—MAYNARD 
M. METCALF. 
ENTOMOLOGY. 
Classification of the Mites.—A paper of much value to stu- 
dents of the Acaroidea has recently been published! by Dr. Troues- 
sart. Itis entitled “ Considérations générales sur la classification des 
acariens, Suivies d’ un essai de classification nouvelles.” The author 
first gives a historical sketch of the classifications that have been pro- 
posed for the group, from that of Latreille in 1795 to that of Canes- 
trini in 1891. He then discusses the characters upon which the class- 
ification should be based, gives the tabular statement of his new classi- 
fication (translated on the following page) and concludes with a useful 
review of the families, subfamilies and genera, with the characters of — 
the families and subfamilies. Dr. Trouessart thinks the mites should 
form the sub-class Acaroidea, of the class Arachnida, and divides them 
into two orders, the Acarina and the Vermiformia—C. M. W 
Color Preferences of the Carpet Beetle.—-During the past May 
the Buffalo carpet beetles ( Anthrenus scrophularie) have been abundant 
on the tulip beds at Hanover, N. H., taking advantage, no doubt, of 
the open windows of the house-cleaning period to fly out and get some — 
pollen for food. In a small bed containing about three dozen tulips, 
three-fourths of which were of red colors, and the rest of white and — 
1Revue des Sciences Naturelles, 1892. : 
