ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 307 
Seventeen North American species of Perdita were known before 
Mr. Cockerell began to study them; of these, two are not considered 
valid, but 55 have been added, bringing the list up to 70 ! Thus, in 
number of species described, Perdita becomes at a bound the largest of 
North American bee genera. 
The author discusses the characters on which the classification must 
be based, the geographical and vertical distribution, the flowers visited, 
and so on. A description of the 70 species forms the bulk of the paper. 
Habits of Polistes.* — Dr. P. Marchal first discusses the nest-making 
of Polistes gallicus, and shows the correctness of de Saussure’s theory 
that the primary form of cell, seen at the outset, and in part in those 
situated marginally, is cylindrical, and that the hexagonal form is the 
result of the association of several cells in a limited space, and of the 
uniformity observed in construction. 
He also shows that honey is collected and stored from the very 
foundation of the nest, when the queen is still alone. This observation 
excludes the theory that the collection of honey is in relation to the pro- 
duction of fertile females. All the larvae get honey as well as animal 
food. 
Thirdly, the author points out that several females hibernate together, 
and may take part in founding one nest. 
Queen-Bee unable to lay Drone-Eggs.f — Prof. C. Grobben refers 
first of all to the well-known fact that queen-bees are sometimes unable 
to produce anything but drones. In other words, on the usual theory, 
none of the eggs are fertilised. But it was the reverse case which 
excited his interest ; that of a queen unable to produce drones. In other 
words, on the usual theory, all the eggs were fertilised. This occurrence, 
though vigorously denied by some authorities on bees, has been repeatedly 
recorded by P. Briifach. Prof. Grobben points out that the phenomenon 
may be due ( a ) to an imperfect nerve-control of the muscular ring sur- 
rounding and normally closing the neck of the receptaculum seminis ; or 
( b ) to defective musculature in that region ; or (c) to an abnormal width in 
the efferent duct, so that thorough closure is not effected; or (d) to over- 
abundant secretion on the part of the accessory glands or the glandular 
epithelium of the receptaculum. He inclines to suppose that the defect 
was in the innervation, but the case has not yet been investigated. 
Flower-haunting Diptera.J — Mr. G. F. Scott Elliott has made 
numerous observations which go to show that flower-haunting Diptera 
are of much importance in pollination. He thinks that his evidence 
clearly proves the colour-sense of the Diptera observe.!, and also that 
they “ are, on the whole, more intelligent than the lower class Hymeno- 
ptera.” “ It is to these Diptera,” he says, “ that we probably owe all the 
neatly made, small and bright-coloured forms (of flowers) which are 
particularly abundant in this country.” The author gives tables showing 
the visits of about sixteen Diptera to various types of flower, and com- 
pares these with the visits paid by Hymenoptera. He suggests that 
Diptera map out the ground as vultures do, and keep flying up and down 
* Bull. Soc. Zool. France, xxi. (1896) pp. 15-21 (2 figs.). 
f Verh. K. K. Zool.-Bot. Gesell. Wien, xlv. (1895) pp. 411 -4. 
X Trans. Eutom. Soc. London, 1896, pp. 117-28. 
