ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 319 
the labrum as a central process, and has as lateral appendages the 
antennary lobes, while it is perforated posteriorly by the orifice of the 
mouth. The original ventral position of the antennas has often served 
as an argument in favour of their being limbs, but they must not be 
considered as equivalent to the persistent ventral appendages. Behind 
the frontal piece is the definite number of true metameres ; the first 
three of these have their appendages converted into gnathites, and the 
head is thus formed ; then follow the three thoracic segments with their 
legs, and then the abdomen, made up of ten true metameres, the 
appendages of which disappear at an early stage. Behind these comes 
the “ anal piece ” into which neither ventral cord nor secondary body- 
cavity are continued, and which has a remarkable resemblance to the 
frontal piece. For, like it, it has two terminal appendages, ventrally 
placed, which later on become the cerci as they move nearer to the anus. 
On the anal piece there is a median dorsal lamina supra-analis, and 
generally two anal valves ; to these in rare cases a lower opercular piece 
is also added. 
A method of notation is suggested whereby the presence or absence 
of the several metameres may be indicated, and the varying characters 
presented by various Insects seen at a glance. 
The author is of opinion that the facts which he here brings forward 
afford a fresh proof of the relationship of the Cockroaches with the 
Thysanura ; while they also show that the ventral plates of the Hcxapoda 
do not correspond to the sternal shields of the same, and as little to the 
ventral shields of the Chilopoda, but that they owe their origin to the 
fusion of abdominal leg-rudiments, flattened out into plates, with an 
unpaired median shield. 
Embryology of Blatta germanica.* — Mr. N. Cholodkovsky has a 
preliminary notice of the results of his studies in the development of 
Blatta germanica. The body-cavity arises within the rudiments of the 
extremities, which are hollow from the beginning, and gradually becomes 
shut off from the nutrient yolk ; eighteen pairs of hollow somites are 
thus formed. During the formation of the endoderm the cavity of the 
somites divides, as in Peripatus, into three portions, one of which is, 
in all probability, homologous with the segmental infundibulum of 
Peripatus. In the later stages of development this division disappears. 
The permanent body-cavity is of mixed origin, for it contains remains 
of the primitive somite-cavity, schizocoel - spaces, and remains of 
the primitive cleavage-cavity. The heart is formed in the manner 
described by Schimkewitsch, and its cavity is a derivative of the 
primitive cleavage-cavity. The fat-body and the sexual cells arise 
from the yolk-cells, which in certain stages of development wander into 
the body-cavity. 
Transformations of North American Lepidoptera.j — Mr. H. 
Edwards has published what ought to be a very useful bibliographical 
catalogue of the described transformations of North American Lepido- 
ptera. Of some groups, such as the Noctuidae, very little is yet known, 
but the subject is one of great interest and importance. 
* Zool. Anzeig., xiii. (1890) pp. 137-8. 
t Bull. U.S. Nut. Mus., No. 35 (1889) 147 pp. 
