PTYCHOPTERA. 129 



Another time Hunter allowed some flies to feed plentifully, 

 and then found the crop quite full, as well as the intestines. 

 Insects have no absorbents; the chyle, which is a clear, 

 greenish fluid, with round oval corpuscles, is supposed to 

 transude through the coats of the intestine into the abdo- 

 men, where it meets with the blood in the ill-defined veins 

 that permeate the body. (See ' Owen's Lectures on Comp. 

 Anat/)* 



The tracheal vessels or breathing organs have been noticed 

 In the chapter on spiracles 'and tracheae. 



The nervous system is similar to that of other insects, 

 consisting of two spinal cords or threads, exhibiting a series 

 of knots or ganglions. The Ely has one in the head, a very 

 large one in the thorax, and one, or sometimes two, in the 

 abdomen; these give out nerve-branches to the wings, 

 halteres, and legs. 



In looking at a slide of Culex observe the length of the 

 coxa, and the small joint called trochanter, between the coxa 

 and femur. 



If possible, obtain the male of Culex annulata with its 

 magnificent antennae and feathered palpi, and the female of 

 Culex pipien* for the display of the suctorial mouth. 



PTYCHOPTERA. 



This is one of the family of Tipulse, Crane-flies, or 

 Daddy-long-legs, which abound in the neighbourhood of 

 water, and are recognised by their black and yellow bodies 

 and spotted wings. The larva is an aquatic worm, and 

 the pupa has a curious, long, thread-like appendage, 

 through which it breathes. We find it in shallow water at 

 .the brink of muddy ponds. 



The wing is a good study after that of the Gnat, as 

 an example of wings without scales, and of the peculiar 

 veining of the Nemocera. The costal vein is the one which 

 borders the fore part of the wing, ending at the tip. The 



* The stomach of the Fly, mounted in balsam, is nn interesting 

 object, and kept in most collections for sale. 



9 



