﻿OF CORYDALU3 CORNUTUS. 167 



The cerebellum, or first ventral ganglion, is situated within the head, just posteriorly 

 to the cerebrum, beneath the oesophagus. It is large, cordate in form, and gives off" an- 

 terior branches to the mandibles, maxilla?, and antennae, and posteriorly the prothoracic 

 commissures to the prothoracic ganglion. The frontal ganglion is large and triangular. 

 It gives off anteriorly two branches to the labium, several minute branches laterally, 

 and posteriorly a single trunk, which, passing beneath the cerebrum, is applied to the 

 oesophagus, to which it sends off numerous minute branches, and is finally lost in it. 



Two small respiratory ganglia also exist upon each side of the oesophagus, connected 

 together by a short commissure and with the cerebrum by means of a similar commissure. 



The ventral chain consists of eleven ganglia, excluding the first or cerebellum ; three 

 thoracic and eight abdominal. 



The thoracic ganglia are considerably larger than those of the abdomen, are hexago- 

 nal in outline, and present an elliptical longitudinal swelling on each side of their middle 

 line. The commissures connecting them are at first widely divergent, and then conver- 

 gent so as to leave wide elliptical spaces between them. The first thoracic or the pro- 

 thoracic ganglion is situated at the posterior part of the prothorax, and gives off laterally 

 branches to the muscles which occupy the prothorax and a large branch to the first pair 

 of legs. The second thoracic or the mesothoracic ganglion is situated just behind the 

 centre of the mesothorax, and is the largest of the thoracic ganglia. It gives off laterally 

 nerves to the first pair of wings, three branches to the muscles occupying the cavity of the 

 mesothorax, and a large branch to the second pair of legs. The third thoracic or the 

 metathoracic ganglion is situated very nearly in the centre of the metathorax, and is a 

 very little smaller than the prothoracic ganglion. It gives off laterally a large nerve to the 

 second pair of wings, three nerves to the muscles within the metathorax, and a large 

 branch to the posterior pair of legs. 



The abdominal ganglia are small trapezoidal knots, and, with the exception of the 

 first and last, are placed at the commencement of their respective abdominal segments ; 

 the first being situated near the centre of the first abdominal segment, the last in the 

 posterior part of the same segment which contains the one immediately preceding it. 

 They are of nearly uniform size, and, with the exception of the last one, send off six 

 nerves on each side to be distributed to the parts within the corresponding segment. 

 The last ventral ganglion supplies the eighth and ninth abdominal segments. 



In the larva, as in other Neuroptera, several simple eyes are substituted for the com- 

 pound eye. In this insect they are six in number, and situated so as to look laterally 

 and forward. The cornea is convex externally, and internally projects into the eye in 

 the form of a cone with a rounded apex, which arrangement supplies the deficiency of 

 a crystalline lens. The cone is not distinct from the cornea, and both are formed of thin 



