57 
General Terminology. 
Despite the contention of Snodgrass, 1910a, the terms dorsum, 
latus, and venter should refer to the back, side, and belly of the 
entire insect (Smith, 1906), while the terms tergum (or notum), 
pleuron, and sternum should be used to indicate the entire dorsal, 
lateral, and ventral regions of a single segment. Sclerites of the tergal 
or notal region are called tergites; those of the pleural region are 
called pleurites; and those of the sternal region are termed sternites. 
The term suture may be applied to impressed lines, or to the 
space between approximated plates, or to the constriction between con- 
secutive segments, or to the line formed by the approximated external 
lips of an inpocketing or infolding of the body wall. The internal ridge 
formed by such a fold may be called an implex (or implica). The 
transverse implex, or internal fold, of the dorsal region between two 
consecutive segments is called a phragma. The phragma being formed 
as an infolding of the body wall, is composed of two more or less closely 
appressed lamellae. If the anterior lamella of the two forming the 
phragma, is strongly chitinized, while the posterior one is membranous, 
the phragma appears to belong entirely to the segment in front; if the 
posterior lamella is strongly chitinized, while the anterior one is mem- 
branous, the phragma appears to belong entirely to the segment behind 
it. The implex between the pleurites es and em (fig. 1) is called an 
apodeme. 
Internal processes (i. e. protuberances or projections which are 
not ridge like) of the sternal region are termed apophyses. These 
may occur singly (monapophyses) along the mid-ventral line, or in 
pairs (diapophyses) one on either side of the mid-ventral line. The 
unpaired type is illustrated by the spina, or internal process borne on 
sternite ss (fig. 1). The paired apophyses may unite at their bases, while 
their distal ends remain free, forming the furca or forked internal 
process borne on sternite fs (fig. 1). All internal ridges, processes, etc., 
are termed the endothorax. 
Intersegmentalia. 
In front of the principal tergal, pleural and sternal sclerites, are 
small detached plates called intersegmentalia. These intersegmental 
sclerites belong partly to the segment in front of them, partly to the 
segment behind them. The tergal intersegmentals are called inter- 
tergites (fig. 1, à) They are well developed in such insects as Cory- 
dalis. The pleural intersegmentals (fig. 1, <p) are designated as inter- 
pleurites (anterior and posterior). They are easily seen in Corydalis; 
and in Perla, they are represented by a number of small plates in the 
