ZOOLOGY. 487 
arises from the primitive band, and apparently corresponds to the 
“ faltenblatt” of Weismann and others, he calls the “ amnion.” 
Scarcely has the primitive band sunk down into the yolk, than it 
immediately greatly increases in size and length, until from being 
only twice as long as broad, and confined to one side of the egg, 
it surrounds the yolk. At this time the segments are indicated, 
and the rudiments of the appendages of the head and thorax 
appear. At a little later stage, the rudiments of ten pairs of ab- 
dominal feet appear, corresponding to the number of abdominal 
segments (in Sphinx). Ten abdominal segments may be set down 
then as the normal number in the Lepidoptera. The embryo with 
fully formed organs remains surrounded by the yolk, which it “gulps 
down its mouth parts, which meanwhile have been perfected.” It 
then devours the “‘amnion,” and finally the external “ serous mem- 
brane.” It has now obtained its characteristic colors and hairs, 
and lies curled up on its ventral side until it gnaws through the 
chorion and effects its escape from the egg-shell. From Kowa- 
leusky’s observations, we should judge that the Lepidoptera at 
first, though differing in some important respects from other in- 
sects, in others develop like Libellula, Telephorus and the Hemip- 
tera and other endoblasts. In this respect, perhaps of not much 
importance, the development of the Lepidoptera is quite different 
from that of the Phryganeide. This, perhaps, indicates that there 
has been no genetic relation between the moths and caddis flies. 
Later, after the germ is formed, with indications of segments, the 
embryo resembles that of Diptera and Hymenoptera.—A. S. P. 
Tue Purrine or THe Car.— Since the vocalization of rodents 
has lately been a subject of study, it has occurred to me to inquire 
into that of one of their mortal enemies. Has any one expounded 
fully the mechanism of the purring of a cat? 
The facts are these. The purr is a double or to and fro sound ; 
ìt accompanies the breathing of the animal and is a respiratory 
Phenomenon. It is in fact a vocalization, with the mouth closed. 
The vibration attending it is felt all over the chest and no farther, 
except in the throat. | 
On auscultation of a pussy during the purr, I found a very 
Musical rumbling sound permeating the lungs throughout. Its 
character is changed, however, when the larynx is compressed ; 
coming higher as the voice does with narrowing of the glottis. 
