1927] Thoracic Sclerites and Wing Bases of the Roach 61 
The spinasternite ss of Figs. 1 and 5 is not very greatly 
elongated in the prothoracic region, but in the mesothorax it is 
long and slender. The spinasternite of the metathorax is atro- 
phied, or it is indistinguishably united with the furcasternite fs , 
in this region. The spinasternite ss of Fig. 1, bears the spinal 
pit, or spinacava sp, which is the external manifestation of the 
invagination forming the internal, median, unpaired apophysis 
called the monapophysis, or spina spi, of Fig. 5, which serves 
for muscle attachment etc. 
The internal sternal processes, such as the furca fu and 
spina spi, may be called the endosterna, and as was mentioned 
above, these endosterna serve tor the attachment of muscles 
etc. As was suggested by Crampton, 1918, instead of designat- 
ing muscles by their function etc., it is preferable to designate 
them by their points of origin and insertion; and if this method 
be followed, we may speak of the furco-apophysal muscles, the 
furco-coxal muscles, furco-trochanteral muscles, etc., or the 
profurco-mesofurcal muscles, prospino-mesospinal muscles, etc., 
and the terms are self-explanatory. 
In the three thoracic segments (Fig. 1) a pre-coxal bridge 
composed of the sclerites pc and ac connects the basisternite bs 
with the episternum es. The sclerite pc is very loosely connected 
with the pleural region in the meso- and metathorax, and may 
possibly represent the sclerite called the lateropleurite, while 
the sclerite ac which is well developed and is connected with 
the sternal region in the mseo- and metathorax, may represent 
the laterqsternite ; but provisionally, at least, I have followed- 
the interpretations indicated by the labelling, (see list of abbre 
viations) until the matter can be definitely determined. 
In the meso- and metathorax, a ventral prolongation of 
of the suture s (Fig. 1) demarks the preepisternum pes or an- 
terior marginal sclerite, which bears an internal protuberance 
for muscle attachment. In front of this region is a “dimple- 
like” impress, or depression labelled i in Fig. 1, which marks 
the location of an internal tumulus, or protuberance labelled 
en in Fig. 5, to which certain muscles are attached 
An infolding (or “inpocketing”) of the integument of the 
pleural region forms an internal ridge, or endopleuron ep of Fig. 
