28 



AN ACCOUNT OF BRITISH FLIES. 



corrugated ; from this end arises the small intestine, which has a 

 double flexure. The large intestine is swollen, and its walls are very 

 much folded ; it passes into a narrow rectum. 



At the base of the chylific ventricle open four Malpighian tubules, 

 each being long and coiled. 



The Respiratory System consists of two rows of lateral trachea, 

 united to one another by a tracheal tube in each segment. Nine of 

 these connecting tubules send off a tube to the stigmata, and other 

 tubes ramify in other parts of the body. 



Nervous System. — We were unable to make out the nervous system 

 of the larvEe examined, so append Kunckel's description verbatim : 



Fig. 5. — Alimentary Canal of Larva. — a, salivary gland ; b, oesophagus ; c, chy- 

 lific ventricle ; d, small intestine ; e, large intestine ; f, rectum ; g, Malphigian 

 tubules. 



" Le systeme nerveux, compose de ganglion arrondis, relies par de 

 connectifs, et au nombre d'une paire environ par segment, n'a pas 

 ete assez soigneusement etudie pour que je puisse le d6crire. II en 

 est de meme du systeme circulatoire." 



The natural position of the fleas has caused much discussion. 

 Lamarck considered them Diptera on account of their transformation. 

 Duges considered them nearly related to the Hymenoptera ; others 

 to the Hemiptera, on account of the rostral shield. 



Latreille placed the flea between the Hemiptera and Diptera, as 

 did also Westwood, raising them to an order called Aphaniptera (of 

 Kirby). They are now considered true Diptera, and according to 

 Osten-Sacken are a degraded genus of the family to which belong 

 the small MycetophilcB, that live in mushrooms during their larval 

 state. Their metamorphoses certainly agree in many points. The 



