230 
EDWARD A. MINOHIN. 
into the intertergal membrane ( i.m .), which again becomes 
continuous with the tergum immediately behind, the whole 
forming a continuous chitinous investment. The letter a., figs. 
1 and 2, denotes the most anterior extremity of the sixth tergum, 
to which the longitudinal tergal muscles (m. 1 and m. 2) are 
attached ; r. is a ridge close behind this part, the space between 
a. and r. being usually overlapped by the hinder part of the 
fifth tergum. These parts are present between every pair of 
terga, but between the fifth and sixth are found in addition the 
peculiar glandular pouches (P., figs. 1 and 2) above mentioned. 
As may be seen, they are lined by a cuticle continuous with 
that of the intertergal membrane (c. 1.), which is produced into 
numerous stiff hairs, which bend towards the opening of the 
pouch. Below this cuticle is a layer of small flattened cells, 
with somewhat irregularly-shaped nuclei ; this layer is evidently 
continuous with the hypodermic layer beneath the intertergal 
membrane (figs. 2 and 4, u. /.). These cells are crowded very 
close together, and their outlines are very hard to make out. 
Beneath this layer again comes a number of columnar cells with 
very distinct outlines, forming one layer on the dorsal side, 
and two or more on the ventral side of the pouch (/. /.). These 
cells have large rounded nuclei, each with a distinct nucleolus, 
and their cell contents are very granular. Outside all is a 
basement membrane continuous with that of the hvpodermis. 
The tergal muscles pass immediately under the pouch, but I 
have satisfied myself, both by sections and by dissecting care- 
fully, that the pouches have no special muscles. In fig. 3 are 
shown some of the hairs highly magnified. They are hollow 
and swollen at the base, and in a chloride of gold preparation 
processes of the cells of the upper layer (u. I .) can be seen 
running into them from below; sometimes nuclei are to be seen 
inside the swollen base. These hairs exactly resemble those 
found lining the abdominal stigmata, which are branched in 
exactly the same manner. Their chitinous nature is evident 
from the fact that if one of the pouches be macerated for a 
sufficient time in caustic potash (30 per cent.) nothing is left 
but the hairs and the cuticle on which they stand. 
