24 COMPARATIVE ANATOMY. 



4. Order Lepidoptera. 



41. Larva of Privet Hawk Moth (Sphinx lig-ustri). 

 Bristles have been inserted into the spiracles of the right 



side. 



Rolleston, p. 73. 



42. Pupa of the same. 



43. Larva of the same, dissected to shew the nervous 

 system. 



It has been laid open on its superior surface, and the 

 digestive system removed, with the exception of a piece of 

 the oesophagus, which has been pinned back, in front of the 

 head. 



The nerve-system consists of twelve ganglia, arranged in a 

 linear series along the ventral surface of the larva. The first 

 pair of these are the cerebral ganglia, situated immediately 

 above the oesophagus. They are connected by the usual nerve- 

 collar, embracing the oesophagus, with the first post-oral ganglion. 

 The terminal ganglion of the series is composed of two ganglia, 

 closely opposed to ea^h other, from which a leash of nerves is 

 given off to the terminal segments of the body. 



Rolleston, p-. 82. 



44. Larva of Goat Moth (Cossits ligniperda), dissected to 

 shew the internal organs. 



The integument has been- divided down the medio-dorsal 

 line and pinned out on each side. 



Occupying the greater part of the body-cavity and investing 

 the contained viscera is a mass of lobulated adipose tissue, 

 known as the ' fat body ' or ' rete,' which disappears almost com- 

 pletely in the c imago' of those insects whose metamorphosis is 

 complete. 



In the median line is the digestive tract, which passes, 

 without forming any convolutions, direct from mouth to anus. 

 The walls of the oesophagus are thin, and thus readily distin- 

 guish it from the thick-walled, opaque, corrugated stomach. 



A little way below the pylorus the intestine receives the 

 common ducts of the tubular renal organs, the so-called 'Mal- 

 pighian vessels.' The common duct on each side bifurcates, and 



