, 266 ANATOMY. 



contract the body during expiration. They appear to be wanting in 

 smaller coleopterous larvae, which are enveloped in a horny case ; in 

 the robust fleshy caterpillars there lies beneath them a third layer of 

 muscles, which take the same direction as the preceding, but differ 

 from them by their shortness and their separation into several parallel 

 fasciculi. They may be called the smaller oblique dorsal and ventral 

 muscles, and those above described as the larger superficial ones, and 

 the smaller ones as the deeper. 



We observe, besides these ventral muscles which run parallely in 

 the longitudinal axis of the body, others which connect the dorsal plate 

 of each segment with the ventral plate. They originate contiguously 

 to the deep oblique ventral muscles with a broad basis, contract pyra- 

 midally by degrees, come then outwards, close to the direct ventral 

 muscles, and ascend on the outside of the straight dorsal muscles to 

 the dorsal plates, inserting themselves contiguously to the deep oblique 

 dorsal muscles upon the dorsal plate. I call them musculi ventri- 

 dorsales. In larger caterpillars, for example, the Cossus ligniperda *, 

 we can distinguish several layers and bundles of these muscles, and it 

 consequently is not difficult to make the number of the muscles of a 

 caterpillar amount to 4061 if, as Lyonet maintains of the goat-moth 

 caterpillar, each particular fasciculus be a distinct muscle-)-. 



Exteriorly, contiguous to these muscles, there lie beneath each 

 other, and close to the lateral wall of each segment, several fasciculi 

 of oblique and crossing muscles, which strengthen still more the con- 

 nexion, and which, from their situation, may be called the lateral 

 muscles. With their diverging ends they embrace the spiracles of the 

 caterpillar, and they appear to assist chiefly in closing them after 

 expiration. 



The muscles of the three first segments, which subsequently form 

 the thorax, are more numerous, for besides the usual connecting 

 muscles we here also find those of the legs, as well as the commence- 

 ment of the future muscles of the wings. 



The longitudinal dorsal and ventral muscles are here in general 

 narrower, that they may make room for the other muscles, yet they so 



* Consult Lyonet, Traitd Anatomiquc, &c. a la Haye, 1760, 4to. PI. yi. vii. & viii. 



f According to Lyonet, the number of muscles found in the head amount to 228, 

 those of the body to 1647, and those of the internal organs to 2186, making an aggregate 

 of 4061. Traite Anal, p. 584. 



