Introduction to A uimal Morphology. 3 9 1 



are many tracheae on its papillary ridges, which in the 

 aquatic larvce of many dragon-flies are extended into trachei- 

 ferous lamella?, named frachcal gills* which by the opening 

 and shutting of the anus are kept bathed with currents of 

 water, and thus serve as respiratory organs. Some Hymen- 

 opterous and Pupiparous Dipterian larvce have no anus, and in 

 ant-lion larva the rectum, thus cut off from the stomach, 

 becomes a spinning apparatus, with a fine outlet, and 

 receives the Malpighian tubes. In the larvce of Dyticus 

 and Ilemerobius, as well as in Myrmeleo, there is no mouth, 

 but there is a large opening at the point of each of the 

 powerful maxillce leading by a canal into the oesophagus. 



Salivary glands are usually present (absent or 

 small in Ephemeridoe, Odonata,Scalidse, Aphides, &c.) 

 They are two long, lobed pouches in Termes ; tortu- 

 ous tubes in Beetles, Diptera, and Lepidoptera, or 

 1-3 pair of acinose glands in Hemiptera and Or- 

 thoptera. Panorpa has six large glands in the male, 

 and only one minute pair in the female. The duct is 

 dilated in Mantis, Lucilia, &c. Fine longitudinal or 

 tortuous brown or whitish Malpigliian tubes open into 

 the intestine (except in Podurae, Coccidte, Aphis, and 

 Chermes), but present in Lepisma and in most other 

 insects. There are four in most Diptera and llemip- 

 tera, six in Lepidoptera and Neuroptera, four or six 

 in IV-etlcs. They open close behind the stomach in 

 llvmc: Diptera, Cicada?, Lepid<pter.!, \c. 



have usually the same number of tubes as 

 adults except in I>-*-s, whose larva* have only four. 

 rarely branch, but sling-likn unions between 

 th ir ends arc jntmd in some, and soinetim ilar 



^c arc tli 

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