ZOOLOGY. 451 



goverument, in order that he may always have a reserve of power with 

 which to meet aspiriug rebellion, so it is to the general advantage that 

 carnivorous insects should abound in larger numbers than could find 

 sustenance in the ordinary surplus of insect reproduction. They will' 

 then be prepared to concentrate an overwhelming attack upon any group- 

 of insects which become suddenly superabundant. It is evidently im- 

 possible, however, that this reserve of predaceous species should be 

 maintained, unless they could be supported, at least in part, upon food 

 derived from other sources than the bodies of living animals." (A. N., 

 XV, 323-327.) 



Wings of Insects. 



The details of structure of the wings of insects and the contiguous 

 parts, especially those of the family Libellulidse, have been investi- 

 gated by Mr. R. von Lendenfeld. The monograph of the alar struct- 

 ures of the Dragon-flies is especially noteworthy. " Sixty-two separate 

 skeletal parts are named and described," and also "16 muscles and 2 

 ligaments." "A diaj^hragm of chitin separates the muscles for the wings 

 from those for the legs; the exoskeleton is made up of thin chitinous 

 plates. There are various methods of articulation, some of which ara 

 exactly comparable to those that are found in the vertebrata." 



The Libellulidse and "i!^europtera planipennia" are considered by Mr- 

 von Lendenfeld to be the lowest of typical insects, on account of thai 

 equality in size of the wings, while those "with one pair of wings appear 

 to be the most highly organized and possess the largest brain." The 

 rank of the other groups is sought to be determined by the relative 

 development of the two pairs of wings. It is probable, however, that 

 the logic emi^loyed, as well as the conclusious deduced, will be opposed 

 by many entomologists. Probably more satisfactory are the author's 

 observations of the mode of flight. 



A method for instantaneously photographing insects' wings was de- 

 vised and is detailed by Mr. von Lendenfeld. "Two phases are to be 

 distinguished in the movement of the wing — the movement from behind 

 forwards, and from in front backwards. In both, however, there is an 

 upwardly-acting force; with this there are associated other move- 

 ments, resulting in the course of the wing being a more or less compli- 

 cated curve, the directions of which depend, of course, on the extent to 

 which these other forces .act." (J. R. M. S. (2), II, 184-185, from Sitz- 

 ungsber. Akad. Wiss. Wien, LXXIIL, 289-37G, with 7 pi.) 



Relations of Devonian Insects to existing types. 



The fossil insects have been for some years the special subjects of Mr. 

 Samuel H. Scudder's studies, and the conclusions which ho has reached 

 respecting the relations of the Devonian forms to later ones have been 

 published, and are as follows: 



(1) The insects have preseryed their general type of wing structure. 



