62 
product, an anterior region hyp (hypopteron) may become secondarily 
marked off by the formation of a new suture. Audouin, 1820—1821, 
at first termed it the hypopteron. Later however, (A udouin, 1824 and 
1832) he included it, together with the tegula, tg, under the designation 
parapteron, erroneously thinking that the two are homologous in dif- 
ferent insects. Jordan, 1902, calls it the “peristernum”. Hopkins, 
1909, terms it the “preepisternum” — a term which Snodgrass, 1909b, 
at first accepted; but later (Snodgrass, 1910b) changed it to “pre- 
pectus”, in the Hymenoptera. Enslin, 1912, calls it the “praesternum”, 
in the sawflies. 
An upper region aes, the anepisternum is sometimes marked off 
in the dorsal region of the true episternum es, in such insects as the 
Diptera, Neuroptera, and many Lepidoptera. It is frequently mistaken 
for the entire episternum. The episternum (or its homologue), 
however, always extends along the pleural suture (when this is 
present) fromthetoptothe bottom of the pleuralplate (i. e. from 
the wing fulcrum to the coxa), in all insects, and without exception. In 
the Diptera, the anepisternum is called the “mesopleura” by Osten- 
Sacken, 1884. The term mesopleura is always applied to the pleura 
i. e. both flancs) of the mesothorax, so that this term is hardly applicable 
to the sclerite aes. I have adopted Osten-Sacken’s term “sterno- 
pleura” (slightly modified to sternopleurite), however, in referring to 
the fusion product of the lower portion of the episternum, etc., united 
with the sternum, in the Diptera. 
In the Blattidae, the trochantin, #, is a large triangular plate, 
from which a smaller plate t/, the trochantinelle, is constricted off, 
in the prothoracic region. The smaller plate in! is always mistaken for 
the entire trochantin, in such cases. In Corydalis, and other Neuro- 
ptera, the trochantin, tm, together with the small marginal region ac 
(fig. 1) and the lower portion of the episternum (cut off by the dotted 
line indicated in the figure as a continuation of the suture marking off 
the sclerite ac) all unite to form a compound sclerite pin (the pleuro- 
trochantin) or fusion product of the lower portion of the pleural 
region, with the trochantin. This sclerite was formerly termed the 
“katepisternal complex” (Crampton, 1909) but this designation is too 
cumbersome. The compound sclerite pin is always mistaken for the 
trochantin #2, alone, but the trochantin itself never assumes this shape, 
nor does it extend into the sternal region in the way the sclerite in 
question does. Furthermore, despite the statement to the contrary by 
Snodgrass, 1909b, the trochantin never intervenes between the epi- 
sternum and the coxa, for the episternum, or its homologue, always 
extends from the top to the bottom of the pleural plate, and in those 
