PODURIDS. 135 



The Abbe Bourlet adopted the same view. On the other hand 

 Burmeister placed the Thysanura as a separate tribe between 

 the Mallophaga (Bird Lice) and Orthoptera, and Gerstaecker 

 placed them among the Orthoptera. Fabricius and Blainville 

 put them with the Neuroptera, and the writer, in his "Guide to 

 the Study of Insects," and previously in 1863, ignorant of the 

 views of the two last named authors, considered the Thysanura 

 as degraded Neuroptera, and noticed their resemblance to the 

 larvse of Perla, Ephemera, and other Neuroptera, such as Rha- 

 phidia and Panorpa, regarding them as standing "in the same 

 relation to the rest of the Neuroptera [in the Linnsean sense], 

 as the flea does to the rest of the Diptera, or the lice and Thrips 

 to the higher Hemiptera." 



After having studied the Thysanura enough to recognize the 

 great difficulty of deciding as to their affinities and rank, the 

 writer does not feel prepared to go so far as Dana and Lubbock, 

 for reasons that will be suggested in the follow- 

 ing brief account of the more general points in 

 their structure, reserving for another occasion a 

 final expression of his views as to their classifi- 

 cation. 



The Poduridse, so well known by name, as 

 affording the scales used by microscopists as 

 test objects, are common under stones and wet 

 chips, or in clamp places, cella/s, mushrooms 



and about manure heaps. They need moisture, ,, 



156. Smynthurus. 

 and consequently shade. They abound most in 



spring and autumn, laying their eggs at both seasons, though 

 most commonly in the spring. During a mild December, they 

 may be found in abundance under sticks and stones, even in 

 situations so far north as Salem, Mass. 



The body of the Poduras is rather short and thick, most so in 

 Smynthurus (Fig. 156), and becoming long and slender in Tomo- 

 cerus and Isotoma. The segments are inclined to be of unequal 

 size, the prothoracic ring sometimes becoming almost obsolete, 

 and some of the abdominal rings are much smaller than others ; 

 while in Lipura and Anura, the lowest forms of the group, the 

 segments are all much alike in size. 



The head is in form much like that of certain larvse of Neu- 

 roptera and of Forficula, an Orthopterous insect. The basal 

 half of the head is marked off from the eye-bearing piece (epi- 



