Sadars 
2 eae 
1914] A Structural Study of Caterpillars. 123 
EXPLANATION OF FIGURES. 
Plates XVII and XVIII—Dissection of the thoracic muscles of Phaeocyma 
sp., following Lyonet’s lettering, and nearly following his order of dissection. 
The muscles not hatched, which appear in the various layers are those which 
appear more distinctly in succeeding ones. The dorsum of the mesothorax, and the 
prothorax, especially in front are incomplete. 
oes. suboesophageal ganglion. 
gang. T!. First thoracic ganglion. 
gang. T2. Second thoracic ganglion. 
gang. A'. First abdominal ganglion. The ganglion of the metathorax lies 
near the letter c of that segment, under the muscles c. 
tr. Functional trunk-trachea of the thorax. 
sp. Al. First abdominal spiracle. 
D, A, B and E at the lower edge of Fig. 1, and E on Fig. 2, belong to abdominal 
muscles, the latter extending forward well into the thorax. 
Rudimentary crossed muscles are shown in Fig. 1, overlying the prothoracic 
ganglion. 
In Fig. 6 the stippled areas represent the position of the wings; they underlie 
all the muscles except the long fibres of T and w. 
sp. in Fig. 6 is the rudimentary second thoracic spiracle, in Figs. 4 and 5 
m indicates its trachea. 
In this and most of the other figures the musculature is shown as it appears 
when the caterpillar is opened and spread out, the muscles nearest the body cavity 
appearing superficial, and the last layer of dissection representing the ones close 
to the skin. In this figure the head was cut in several pieces to enable the pro- 
thorax to be spread out flat, and the broken lines represent the mid-dorsal and 
midventral lines, marked by the position of the dorsal vessel and nerve cord. 
The small muscles of the legs are not shown. 
Plate XIX.—Metathorax of Noctua baja (?), dissected in six stages, following 
approximately Lyonet’s directions and using his lettering. 
gang. Ganglion. 
sy. Fork of sympathetic nerve. 
a. Rudiment of middle thoracic spiracle and its trachea. 
im. Rudiment of an imaginal muscle. 
The wing is shown in the deepest dissection and coarsely dotted. 
Plate XX—The middle abdominal segments of Nephelodes minians (?) 
similarly dissected in six stages, in the following order: 
b 2, 
4, 3, 
5, 6. 
Plate XXKI—Middle segments of Sphecodina abbotu, dissected in the same 
order, in four layers. 
tie irachea: 
Plate XXII—Middle segments of Malacosoma americana dissected in four 
layers in the following order: 
7g & 
3, 4. 
d. v. Dorsal vessel or heart. 
w. h. wings of the heart. 
sp. Spiracle. 
tr. trachea. 
gang. Ganglion. 
sy. Fork of sympathetic nerve (belonging to preceding segment). 
The position of the hooks of the proleg is indicated by a series of bars. 
5 is a small muscle in the planta. 
