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Psyche 
[April 
have observed it in other groups of insects, notably by Fabre on 
Scarites gigas Fabricius (Coleoptera) ; by Holmes on Ranatra 
sp. (Heteroptera) ; and by Rabaud and by Bohn on several 
orders (Bouvier, 1919, pp. 79-89). In Macrosiphum the habit of 
dropping to the ground and remaining motionless for a time is 
evidently a means of eluding a pursuing enemy. 
Summary of Section IV. Many species of Macrosiphum 
possess the habit of “death-feigning” when disturbed. 
2. The habit is exhibited by Macrosiphum tanaceti in all of 
its stages, except in the first instar. 
V. Parturition. At birth, the caudal portion of the nymph 
appears first at the vaginal slit. The antennae are directed pos- 
teriorly and closely appressed to the body walls. The legs and 
cornicles are also in the same condition, the appendages thus 
following the general contour of the body. The tarsi of the 
metathoracic legs are in intimate contact with each other, 
forming at the caudal portion of the abdomen a conspicuous 
acutely subconical projection. The color of the nymph at birth 
resembles that of the freshly molted nymph or adult. The body 
and appendages are uniformly light apple-green and glossy, and 
the eyes are reddish vermillion. The enveloping membrane 
covering the young at birth, which has been described by Webster 
and Phillips (1912) in Toxoptera graminum Rondani, by Baker 
(1915) in Eriosoma lanigerum Iiausman, and by other authors in 
other species of aphids, has also been observed by me in Macro- 
siphum tanaceti. The results of the present work agree with 
Baker’s account in that the envelope ruptures while the nymph 
is partially extruded from the vaginal slit of the mother. The 
nature of this membrane is still in question; although, from my 
observations on M. tanaceti, I am led to believe that it probably 
arises from the follicular epithelium, which persists to this stage 
without degenerating. A more detailed discussion of this sub- 
ject will be given in a later paper on aphid embryology which I 
am publishing. If my observations, therefore, are correct, this 
envelope is not a homologue of the vitelline membrane of the 
eggs of amphigonous aphids, as Webster and Phillips have 
