1900] 



ENTOMOLOGICAL SOCIETY. 



53 



the powerful muscles necessary to move and control the four ample wiogs and the six legs 

 of the creature. 



The abdomen extends far behind, to steady the insect, and to aid in steering its 

 flight ; but in the Libellulidae it is somewhat flattened and ends with a point. In Gordu- 

 ligaster the cylindrical abdomen ends with a knob or swelling, hence the name, a club, a 

 paunch. In Gomphus the abdomen is spatulate at the end. 



July and August are the months in which the, dragon-flies abound. Then every 

 pool, every stream, .is frequented by them. Sometioaea the observer may see them in the 

 act of depositing their eggs. They alight upon the flags, arrowheads and other aquatic 

 plants, and taking suitable positions dip their abdomens into the water, and deposit their 

 eggs in masses upon the stalks and leaves beneath the surface. 



The embryos, in different stages of their growth, have been observed and figured, 

 and the larvfe of various kinds are known. To the possessor of an aqaarium the study of 

 the habi'^s of the dragon-tly, in its early stages, would aff'orJ greit pleasure. 



A dragon-fly larva is a wonderful thing. At first sight the uninstructed observer 

 does nob see much to admire in it, but closer examination reveals features of exceeding 

 interest. One of these is the extraordinary under lip of the creature, which takes the 



form of a jointed arm, furnished at the 

 extremity with nippers for securing its 

 prey. "When not in use this instru- 

 ment is neatly folded under the throat 

 of the larva — it is called " the mask " 

 (Fig 9). Then too, the peculiar ar- 

 rangements by which the insect obtains 

 oxygen, its vital breath, fiom the 

 water, are worthy of notice. It has 

 no head gills, as the fish has ; no 

 branchete like the larva of the Horned 

 Corydalis ; no breathing tube like that 

 of the rat-tailed maggot of Eristalis. 

 The respiratory organs lie within the 

 abdomen, and the water is admitted to 

 them through an orifice furnished with 

 five angulated plates, which open or 

 close as need requires. Ordinarily the 

 process of the alternate admission and 

 expulsion of the water goes on with 

 easy regularity ; but when the creature 

 is alarmed or stimulated by the eight 

 of its prey, the water within its body 

 is expelled with sudden force, and the 

 tiny current, impinging upon the inert 

 volume around, sends the insect for- 

 ward with a rush, as the rocket is sent through the air by the pressure of the gases 

 suddenly generated by the combustion of the materials with which the case is filled. 



The metamorphoses of the dragon-fly are incomplete. A.t the pupd change the insect 

 does not become quiescent, nor does it cease to feed — it retains its active habits and vora- 

 cious appetite. When the time comes for it to assume the imag) state, it climbs some 

 plant or other object till it is clear above the surface, and then its skin bursts along the 

 thor-ix and the perfect insect crawls out of the opening and leaves its old habit, attached 

 by the olaws, as a memorial of its former state. (See Fig. 9.) 



Having thus introduced the Odonafca, and given some glimpses of their habits, we 

 will now notice their classification. 



They are divided into four families : Agrionid.e, Gomphid^, ^schnid.e, and LiBEt/- 

 LULiD^. These are easily distinguished each from the others. 



The Agrionidse have the eyes wide aput and placed apparently on pedicels. 

 The Gomphidse have large eyes, near together, but not touching each other. 

 The ^-ichnidae and Libellulid?e have eyes that are contiguouf. In the former the 

 labial palpi have three joints ; in the latter the joints of the labial palpi number o u) 



Fig. 9.— The left figure repres3nt8 the larva with its pro- 

 truded lip in the act of seizing its prey ; the right shows 

 the perfect insect emerging from its pupal case. 



