566 EMBRYOLOGY OF CHRYSOPA. 
sigmoid band, extending back to the posterior pole of the egg. 
But after the rudiments of the limbs appear, the embryology of 
both genera accords with that of Donacia. I have found that 
the embryology of Gastrophysa ceeruleipennis in its later stages 
also agrees with that of Donacia, (both being Chrysomelids.) A 
study of the development of Nematus ventricosus, shows us that 
its embryology accords with that of Apis mellifica. The forma- 
tion of the blastoderm is as described by Biitschli in Apis,* and 
quite unlike that of the Formicide as studied by Ganin. It also 
agrees with that of the Diptera in most particulars 
There is indeed a remarkable uniformity in the mode of devel- 
opment of the Hexapoda, as much so perhaps as in the Crustacea 
(Malacostraca), and it is difficult to determine what embryologi- 
cal characters may be set down as distinguishing even the different 
suborders. These characters, whatever they may be, do not prob- 
ably reside in the embryonal membranes, or in the relation of the 
primitive band to the yolk. Perhaps they will be found in the form 
of the advanced embryos. For example, we now know that the 
embryos of the Isopod Crustacea only differ from those of the 
Amphipods while in the egg by having the end of the abdomen 
bent over the back, while in the latter (Amphipods) it is curved 
beneath the body, as pointed out by Fritz Miiller. The spiders 
and scorpions also pass through a similar course of development, 
and the Mites (Acarina) are developed in a manner either iden- 
tical with the spiders in some genera, or more like the Hexapods 
in others. We know almost nothing of the embryology of the 
Myriapods, but Newport’s observations on Julus indicate that it 
is developed in an entirely different mode from the Hexapoda or 
Arachnida, a remarkable feature being the persistence of the larva 
in its inner(?) embryonal membrane (faltenblatt of Weissmann) 
for many days after it is hatched. 
There are, however, two modes of development in the Hexapoda, 
depending on the position of the primitive band in relation to the 
yolk. The Hymenoptera, Diptera, and certain Coleoptera (Cur- 
culionide), and the Phryganeide and Poduræ (Isotoma) are ecto- 
blasts, | while the Hemiptera and certain Neuroptera (Libellulide 
O. Biitschli. Zur ee der Biene; Siebold and Kolli- 
Da Snag 1870. p. 519. 
+ I omit any reference to the Lepidoptera, which Dr. Dohrn regards as endoblasts but 
which ri am inclined from some eggs (probably = an Arctian) I have studied to regard 
as developing like the Hymenoptera and Dipte 
