142 Annals Entomological Society of America  [Vol. VII, 
segments into four annulets, illustrated on Plate IX, Figs. 1 
and 2. These are the acro-, pro-, meso- and meta-tergites and 
sternites, separated by the antecosta, precosta and inter-costa. 
The tergopleural suture is indicated only by the position of 
the rudimentary wing, while the pleurosternal one is the 
strongly marked subventral fold, to which several muscles are 
attached. In the abdomen these boundaries are less distinct, 
but the pleurosternal suture can be traced in a general way, 
and the tergopleural must be placed at least a little higher, as 
indicated by the spiracle, which should lie within the pleuron. 
Of the true legs we have a well marked coxa, which is mostly 
membranous in the Sphinx, a strong femur, to which only one 
or two small somatic muscles are attached, and the rudiment 
of a trochanter, which bears the insertion of r. The insertion 
of the various muscles of the leg is beautifully shown by Lyonet, 
in Plate VIII, Fig. 7. In Cossus where the coxa is wholly 
chitinized.k, n,:-p, <8, tj , -vV, x; 6, 0, x) Nie, » ane es tue etere 
The body muscles may be divided as to their origin in the 
embryo into the dorsal and ventral longitudinal systems, and . 
the lateral and ventral transverse ones; the last is not repre- 
sented in the caterpillar by a developed muscle, but its rudiment 
may exist associated with the fork of the sympathetic nerve 
and the ventral diaphragm. This would be 4 of Berlese. The 
lateral transverse muscles are again divided into two sets, 
between which lies couple of longitudinal fibres (E of the 
abdomen) and the trunk trachea, but as the trunk trachea is 
not well developed in the thorax, and replaced by collaterals in 
the body cavity, the muscles must there be treated as a single 
unit. If we consider C, E and G as homologues of E, etc., of 
the abdomen 6 will be the only fibre of the deep set in the 
thorax, as it is in the abdomen. It should be noted that the 
spiracles can migrate without disturbing these fibres, while the 
deep transverse fibres would have to be swept before them. 
The muscles also differ from each other in their normal or oblique 
direction, their length and their insertion. The table annexed 
classifies them, and gives the relations between meso- and 
metathorax, and between the various nomenclatures, omitting 
those muscles which puzzle me. 
