48 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
the same essential peculiarities of minute structure as were described 
by Minot* in the orthoptera. The lining epithelium is thrown up into 
folds so as to form imperfectly differentiated glandular follicles. If the 
epithelium be brushed off, the characteristic arrangement of the mus- 
cular fibers can be seen, Plate VI, Fig. 7. There is an internal coat, com- 
posed of a great number of pale fibers running transversely around 
the stomach and more or less parallel to one another. Outside are the 
longitudinal striped muscles, which are distributed in single bundles, 
1 1, and do not form a continuous layer. Each bundle is composed of 
a number of fibers and pursues its own course ; the bundles are not 
parallel, but sometimes two bundles unite, or are connected by a third; 
their general trend is longitudinal. Finally it must be mentioned 
that numerous tracheal branches penetrate the muscular layers, and 
ramify through both them and the connective tissue. 
EXTERNAL ANATOMY OF THE IMAGO. 
To prepare the external skeleton for examination the following method 
is satisfactory and convenient. The whole insect, either in the fresh 
state or after preservation in alcohol, is placed in a test tube with a solu- 
tion of caustic potash and carefully boiled over a flame for a couple of 
minutes. The specimen is then thoroughly washed with water, to which 
a little acetic acid or vinegar is added to neutralize the alkali. The 
specimen while in this state may be brushed with a camePs-hair pencil, 
and most of the scales removed. It is best to put it next, for twenty- 
four hours, in strong alcohol and to then complete the brushing upon 
the hardened object. With a little care and patience all the hairs and 
scales can be removed without injuring the crust. 
A view of the exoskeleton of the female is given on Plate VIII, Fig. L 
TVe shall follow Mr. Burgess 7 memoir upon the Milkweed Butterfly ,t as 
to the homologies and nomenclature of the parts. The head is more 
triangular in outline, when seen from the side, than in Danais, and the 
eyes,i?, are relatively smaller. The palpi and maxillre are very similar 
to those of the butterfly. The antenna?, «, are thicker and the enlarge- 
ment of the two basal joints is quite marked. The thorax is large and 
compact. The first segment (I) is small, the second (II) by far the 
largest of the three. The prothorax is connected with the head by a 
narrow neck, which is perhaps really the anterior portion of the first 
thoracic segment. This point is better shown in a view of the underside, 
Plate IX, Fig. L The front legs are there removed ; the insertion of 
coxse into the thorax is shown at l l ; just in front of this insertion is a 
thickened ring of hard crust j farther forwards the integument is mem- 
branous, and the prothorax proper becomes directly continuous with 
*Minot,C.S. Hi»tology of thelocnnt (Calopteyiut) : and the crickot (Anabru*) i Chapter X,inSecond 
Keport of the United State* Entomological Commission. 1880. Pp. 188-834. Plates II-Vm. 
t Burgess, Edward. Contributions to the Anatomy of the Milkweed Butterfly (Danain archipput, 
Fabr.). Anniv. Mem. Boston Soe. Nat. Hist.. 1881. 
