Won 2] ANURIDA MARITIMA. 259 
envelopes and their probable connection with similar structures 
in other hexapods is somewhat vague and unsatisfactory. One 
point is clear, however: there are membranes in both forms that 
are attached to the organ, and constitute a structure important 
to the embryo. Lemoine says there are present at first in 
Anurophorus an outer thick “chorion,” which is perforated 
irregularly in numerous places, and an inner very fine vitelline 
membrane. Later, more membranes are formed, the first of 
which appears after the formation of the blastoderm; it is 
described as very fine and not uniform in thickness. The author 
judges it to be formed of many cells identical in origin with the 
blastoderm cells, and calls it the amniotic membrane, naming 
it, however, purely from analogy of form and function. This 
“amniotic membrane” is connected with the dorsal organ by 
an ampulla, which Lemoine calls the ‘amniotic ampulla.” 
Throughout the greater part of development another membrane 
is also present that he considers a true larval skin, as it forms 
on the outer parts of the appendages also. 
Nicolet describes two envelopes for the poduran embryos 
he studied (Podura, Cyphodeirus, Desoria, Smynthurus), the 
outer very stiff and the inner fine, probably corresponding to 
the “chorion ’”’ and vitelline membrane of Lemoine. Oulganine 
(75) describes two similar structures in Achorutes, Anuropho- 
rus, and Degeeria. It is evident that these two membranes 
are found in all these forms, but Lemoine is the only one 
to describe still more. Leaving out the two preblastodermic 
envelopes that are similarly described by all authors, one of the 
inner ones described in Anurophorus and Smynthurus may be 
considered as resembling the crenated membranes described in 
Anurida. This “amniotic membrane” of Lemoine is peculiar 
in its behavior during the life of the embryo. It possesses 
great powers of expansion and contraction, increasing the size 
of the egg by one-fourth or one-third at its largest size compared 
with its smallest. The author goes further and states that in 
contraction a folding of the surface of the embryo takes place, 
giving it a roughly four-sided figure with fine wrinkles over the 
surface. 
No such powers of rapid contraction were seen in Anurida. 
