138 



In the anterior third of the thorax it divides 

 into two smaller portions which pass outwards, 

 and coming in contact with the salivary ducts 

 enter the neck. 



Blood spaces without definite walls occur 

 throughout the body. The thorax especially con- 

 tains large spaces among the muscles, and the 

 complex fat-body which lies between and sup- 

 ports the organ is everywhere bathed with blood 

 fluid. 



The Nervous System 



The ganglionic system in the Culicidae is con- 

 siderably developed. The head ganglia are large 

 and complex. The thoracic ganglia are large 

 and compressed so as to form a large ganglionic 

 mass. The ganglia of this system are as fol- 

 lows : — 



(a) Lying around the pharynx is a gang- 

 lionic ring composed of large supra and infra 

 oesophageal ganglia with their commissures. From 

 these, large nerves go to the eyes, antennae, and 

 mouth parts. 



(6) In the thorax, lying below the oesopha- 

 gael diverticulum and close to the sterna, is a 

 large compound ganglion showing evidence of its 

 origin from the conjoined ganglia. Between this 

 and the head ganglia are two long slender nerve 

 cords, which pass in the neck in close relation 

 with the salivary ducts. From the thoracic gang- 

 lion large nerves pass to the limbs, and posteriorly 

 nerve cords connect it with the first abdominal 

 ganglion. 



(c) The abdominal ganglia lie with their 

 connecting commissures close upon the abdominal 



