416 
coons produced by keeping the larvae hungry, 
Larvae of Thyreus abbotii, of which both di- 
morphic larval forms are common in Cam- 
bridge, possibly sometimes drop one larval 
stage. 
Mr. G: Dimmock was elected secretary and 
Mr. B: P. Mann treasurer, in place of Mr. 
W : Trelease, whose resignation of the office 
of secretary-treasurer was announced. 
10 Nov. 1882.—87th meeting... 
Dr. H. A. Hagen called attention to the 
subject of acceleration of development in the 
larvae of lepidoptera, and especially to its 
occurrence where many larvae are crowded to- 
gether. After referring to some cases men- 
tioned in his paper ‘‘On some insect deform- 
ities” (Memoirs Mus. comp. zool., May 1876, 
v. 2,no 9), Dr Hagen said that Péerts me- 
napia sometimes so hastens the process of 
pupation, when crowded, that the pupa lacks 
the usual encircling thread and is only sus- 
pended by the tip of the abdomen, and, in 
one case the process was so hurried that only 
the anterior part of the chrysalis was formed. 
Mr G: Dimmock exhibited dwarf cocoons 
of Afttacus polyphemus. the dwarfing of 
which was produced by starving the larvae. 
The average weight of the ten dwarf cocoons 
exhibited was 1.2 grams, while the average 
weight of nine cocoons from larvae reared 
in similar circumstances, but not starved, 
was 3.8 grams. It is possible to make the 
larva of A. polyfhemus spin a cocoon when 
it is only between 2.5 and 3 cm. long, by 
gradually diminishing its food-supply; this 
formation of dwarfs by starvation is not pos- 
sible, to the same marked extent, with larvae 
of A cecropia, A. promethea or A. luna. 
The lightest weight of any cocoon of A. 
polyphemus possessed by Mr. Dimmock was 
0.2 gram, but this cocoon was occupied 
by a dead larva. Next in weight was one 
which weighed 0.3 gram, and which con- 
tained a cocoon of an ichneumon. Para- 
sitism usually reduces the weight of cocoons. 
The most promising dwarf cocoon was one 
weighing 1.8 grams, which was very sensi- 
PSTCHE. 
tive to disturbance, the pupa within it writh- 
ing about on slight touch. The pupa of 
A. luna are usually much more sensitiye 
than those of A. polyphemus; their weight 
less, however; the average 
weight of seven well-developed cocoons of 
The weights of 
all the above-mentioned cocoons are proba- 
bly slightly less than they would be if the 
larvae had been reared in the open air. 
Dr. H. A. Hagen showed a very large 
specimen of the £¢ppoboscidae, probably a 
new species, which had been found on a 
swallow. Its length was one centimetre; 
it had no ocelli; its wings were rudimentary, 
not broken off, as is usually the case with 
the females of ¢Afoboscidae, and the round- 
ed rudiments of wings had veins and a 
Dr. Hagen alluded further 
to the number of species of the family and to 
the wide distribution of each species. 
Dr. H. A. Hagen exhibited egg-shells of 
a hemipterous insect, which were found ona 
grape-vine in California. At first sight the 
eggs would be mistaken for those of some 
species of bombycidae, being white banded 
with brown, and barrel-formed. The first 
larval skin remained within the eggs togeth- 
er with a little three-pointed egg-burster. Dr. 
Hagen then described the modes by which 
some larvae with sucking mouth-parts escape 
is generally 
A. luna was only 2 grams. 
marginal fringe. 
from the egg, drawing especial attention to 
the cephalic saw by which the larva of Chry- 
sopa and of other hemerobidae extricate them- 
selves from their eggs. 
Mr. R. Thaxter showed a larva of Papilio 
cresphontes taken by Mr. N. Coleman, in_ 
Berlin, Conn., 13 Oct. 1882. This species 
has been found afew years past about Berlin, 
Conn. 
Mr. G: Dimmock mentioned that out of 
about a dozen pupae of Tkhyreus abbotit 
which he attempted to carry to Germany, in 
1879, not a single specimen survived the 
voyage. Dr. Hagen remarked on the modes 
of packing best suited for carrying pupae on 
oceanic voyages. 
