252 FoRTY-xixTH Report ox the State Museum 



general description given by Dr. Fitch and the more detailed one of Dr.. 

 Packard, as to leave scarcely a doubt of its identity with this species. 

 The insects were found on April 13th in large numbers on the trunks of 

 pear-trees. They appeared to be working up from the ground toward the 

 larger branches. Mr. Powell was fearful that they might injure the trees, 

 but he was assured that they were harmless and their occurrence on the 

 trees was probably accidental. 



Classification and Characteristics. 

 The lodurida are among the most degraded forms of insects: indeed,, 

 some writers have regarded them as not belonging to the Class of Insects, 

 but as being quite nearly allied to the Myriapoda. Nearly all ncent 

 authors agree in referring them to the Order Thysanura, established by 

 Leach in 1796, and in the suborder of CoUembola. Dr. Sharp, in his 

 late publication in the •' Cambridge Natural History," has revived the 

 old Linnaean Order of Aptera ; to include the two suborders, (1) Thy- 

 sanura, and (2) CoUembola. To the former belong the species of 

 Lepisma and allied genera commonly known as " bristle-tails," and to the 

 latter, the Poduridce or "spring-tails." 



A distinctive feature of the Poduridce, separating them from all other 

 known insect forms, is a leaping apparatus near the end of the abdomen. 

 The spring, represented in tigure 22, consists of a basal part usually of a 

 subtriangnlar form, bearing a pair of appendages composed each ot two 

 distinct joints. During life it is flexed beneath the body directed forward,, 

 and held in position by means of a "catch " attached to the under sur- 

 face of the third abdominal segment. On the sudden release of the spring, 

 from the catch, its elasticity projects the insect into the air as if rebounding 

 from a springboard to a distance often of an inch or more. This process is 

 repeated until the insect finds itself in a position of imaginary security. 



Another distinctive feature of this family is " the ventral tube " project- 

 ing from the first abdominal segment, and appearing as a simple tubercle 



divided by a central slit. Various opinions 

 have prevailed in regard to its functions. 

 Sir John Lubbock accepts DeGeer's inter- 

 pretation of it, viz., that it serves as a 

 Fig. 22. -Spring of Schoturus~nivi- sucker and is used in case its feet do not 



COLA, lateral aspect, very greatly rv- i r i • i -i 



enlarged. (Original.) Sufficiently perform their purpose while 



ascending a smooth surface — an adhesive fluid being emitted from it. 



The original description of this species by Dr. Fitch, may be found in 



my Second Report, 1885, page 2^, accompanied with a more detailed 



o 

 one by Dr. Packard. 



