42 Dr. Karl Krapelin on the Pulicidge. 



altered condition. The " mummy-pupEe," however, show- 

 many differences amono- themselves with regard to the closer 

 or looser appression of the appendages of the body, as may 

 be demonstrated by a comparison of the pupee of the Asilidaj, 

 which rest in the ground, and those of Tipulce which live in 

 the water. 



Of anatomical peculiarities of the Diptera especial mention 

 must be made of the " sucking-stomach," which is always 

 present, as also of the large thoracic salivary glands, the 

 eft'erent ducts of which, wherever the buccal organs perform 

 any function, unite into an unpaired closed canal, which, 

 running along in the cavity of the hypopharynx, opens at its 

 extremity. The testes are almost always two ; the Malpi- 

 ghian vessels almost as regularly four. As regards the 

 tracheal system, the constant absence of the first thoracic 

 stigma and the small number of abdominal stigmata are to 

 be noticed ; while the nervous system, as is Avell known, 

 shows all possible forms of development, from the most ex- 

 treme concentration to a very considerable segmentation of the 

 ganglionic chain. 



If Ave turn from this brief account of the Dipterous type to 

 the characters of the Pulicida3, we must admit, in the first 

 place, that in a whole series of points of comparison an agree- 

 ment between the Diptera and the Fleas can be demonstrated. 

 Like the Diptera, the Fleas have a suctorial buccal apparatus, 

 a perfect metamorphosis, and footless larvee ; as in them also 

 the tarsi are five-jointed, there are four Malpighian vessels, 

 and one pair of testes. But, as has already been indicated at 

 page 38, we could only ascribe decisive weight to this agree- 

 ment if all these characters were peculiar to the Dipterous stem 

 alone, and if at the same time, by more detailed comparison, 

 real tenable parallels could be drawn between the different 

 parts of the organs, as between the different stages of develop- 

 ment. This, however, is by no means the case. The number 

 of Malpighian vessels and of testes recurs in the same way in 

 the Rhynchota, and therefore proves no more in favour of the 

 relationship between the Fleas and the Diptera than the 

 number of the tarsal joints or the annulation of the terminal 

 knob of the autennce, which may be recognized in all possible 

 groups of msects. At the first glance more importance seems 

 to attach to the agreement of the two groups in the larval 

 state, which in fact goes so far, that Brauer* has no hesita- 

 tion about arranging the larva of the flea in his group of 

 orthoraphal eucephalous Dipterous larva3. In opposition to 



* Brauei', "Km-ze Charakteristik der Diptereularven," in Verb, k.-k, 

 zool.-bot. Ges. in VVien, 18G9, p. 846. 



