1136 The number of Segments { November, 
with naturalists to designate the head the first segment of the 
body, and as every change in the nomenclature of a distinct part 
ought always to be avoided, unless positively required, through 
fear of creating confusion, we shall not deviate on the present 
occasion from the established mode; but when speaking of itas 
a whole shall consider it the first segment, while the aggregation 
of segments of which it is composed we shall designate individ- 
ually subsegments, distinguishing them numerically in the order 
in which they appear to exist in the earliest condition of the fe- 
tal larva.” 
If we apply the law enunciated by Savigny, and which holds 
good as a rule throughout the hexapod insects, 7. e., that each 
segment of the body of insects bears but a single pair of jointed 
appendages, we find that as the head of insects is provided with 
four pairs of appendages, viz., the antennz, mandibles, first max- 
illæ and labium (or second maxilla), there must be four corres 
ponding segments. 
While the subject becomes clearer when, with Newport, we 
examine an insect in the larval state, the fact that the head of 7 
sects is really composed of but four segments becomes readily 
demonstrated when we examine the embryo at an early stage 
its existence. In our embryological studies on the Thysanurouy 
insects (Isotoma), on Pseudoneuropterous insects (Diplax), on te 
beetles and the flea and Hymenoptera (Mematus ventricosus), "T 
attention was specially directed to this point, and it appeared very 
plain and easily demonstrable that the head of winged insects “ 
all orders consists of four segments (arthromeres) and no mor 
An inspection of the figures published by the different "e 
on the embryology of insects appears to confirm this viet 
our “ Guide to the Study of Insects” (p. 20) we have given @® 
ular view of the four segments of the head and the appendage 
they bear. This view is fully confirmed by our studies om 1 | 
embryology of the locust. The antennz and mouth-parts < 
outgrowths budding out from the four primitive segments A C 
head; the antennz grow out from the under side of the prota 
alic lobes, and these should therefore receive the name of antel t 
lobes. In like manner the mandibles and first and second MA 
: sanurous pr 
| See Embryological studies on Diplax, Perithemis and the Thy 
Isotoma, by A. S. Packard, Jr.; Memoirs Peab. Acad. Sc., Salem, 1871, 
Second Memoir, 1872. This view was stated in the author’s “ Guide® ) also 
of Insects,” second edition. Graber (Die Insekten, Miinchen, 1879, P: 43° oe - 
States that the head is composed of four segments. Bh 
