70 ENTOMOLOGICAL NEWS. [April, 



In the Standard Natural History, edited by J. S. Kingsley, vol. 

 ii, 1884, the orders are: 



I, Thysannra; 2, Dennatoptera ; 3, Pseudoneuroptera ; 4, Neuroptera; 5, 

 Orthoptera; 6, Hemiptera ; 7, Goleoptera; 8, Diptera; 9, Aphaniptera (un- 

 seen wings); 10, Lepidoptera ; 11, Hymenoptera. 



Here 2 and 9 correspond to the Dermaptera and Siphonaptera of the 

 " Entomology for Beginners;" otherwise the orders correspond to the 

 similarly named orders of Prof. Comstock, except that No. 6 includes both 

 his Hemiptera and Physopoda. 



In Claus and Sedgewick's Text Book of Zoology, vol. i, 1885, 

 the orders stand: 



I, Thysannra; 2, Orthoptera; 3, Neuroptera; 4, Strepsiptera (twisted 

 wings) ; 5, Rhynchota (beaked) ; 6, Diptera ; 7, Lepidoptera ; 8, Goleoptera ; 

 9, Hymenoptera. 



Here the Orthoptera includes orders 2, 3 and 4 of Prof. Comstock; the 

 Rhynchota are his Hemiptera; the Strepsiptera (which includes a single 

 family of beetles, Stylopidae, having only the hind wings developed, the 

 front wings represented by pseudo-halteres) and the Goleoptera are equiv- 

 alent to his Goleoptera; the other orders are the same as his. 



Other names sometimes used as ordmal are Plecoptera (folded wings) 

 for the family Perlidae, Stone flies; Gorrodentia (gnawers) for the Mallo- 

 phaga, Psocidse and Termites; Homoptera (same wings) and Heteroptera 

 (diverse wings) for two divisions of the Hemiptera, the one having wings 

 of the same thickness throughout, the other with the front wings as hem- 

 elytra; Enplezoptera (well-folded wings) for Dermaptera. 



On comparing the classification from the ' ' Entomology for 

 Beginners" with the others here quoted, it will be seen that the 

 differences' between them depend very largely on the answers 

 given to such questions as this: Are the groups Platyptera, 

 Odonata and Plectoptera, for instance, of the same value, i.e., as 

 distinct from each other, as the Lepidoptera are from the Hymen- 

 optera? Ever- widening knowledge alone will settle such questions. 



Two things must be remembered in dealing with classification. 

 The first is that very many ordinal, family and generic characters 

 admit of exceptions in the shape of intermediate forms. As Dr. 

 Leidy has said: " Our divisions in nature [are,] to a great extent, 

 matters of convenience."* Secondly, the natural arrangement 

 of the orders and other groups is not linear. It is rather to be 

 compared to the position of countries upon a map, or to the 

 branches of a tree. This latter comparison is especially useful 

 when taken into connection with the evolution of species, 



* Lecture of Oct. lo, 1888, at Biological Department, University of Pennsylvania, Phila- 

 delphia. See also Ent. News, vol. ii, p. 47, at bottom. 



