34 



in length, in which the wings are so wonderfully folded up. When 

 the wings arc fully expanded they measure nearly 1^ inch in 

 Xength, and half an inch wide at their hase, or broadest part. 

 It having been suggested to me that the development of the wings 

 from the folded condition was accomplished by air being forced 

 in through the nervures of the wings, which are hollow tubes, 

 I had recourse to an experiment with a view of proving this, but 

 from what I was enabled to observe, 1 am of opinion that instead 

 of ail* it is a liquid of a gummy natvu'e, and of a greenish colour, 

 that is forced by the effoi-ts of the creatures through tho hollow 

 tubes of the wings ; and when they are fully expanded this 

 liquid dries, becomes transparent, and at the same time stiffens 

 and strengthens the wings. While in the jupa state they are 

 voracious feeders, and nothing comes amiss to them, tadpoles of 

 frogs and toads, shrims, young newts, small fish, &c., and they 

 are armed with a curiously contrived apparatus to catch their 

 prey. This instrument is called a mask in consecj^uence 

 of its being placed over and covers the face and mouth of the 

 creature, and on the approach of any animal it may be inclined 

 to make a meal of, is thi-own out quicklj'. 



With the formidable clasper at the extremity, the creature is 

 secured and conveyed to the mouth and thus held until consumed. 

 The pupa of the di'agon fly are generally seen crawling at the 

 bottom of the pond or over the weeds, but they can swim with 

 rapidity, in which action the legs take no part, they are laid 

 close against the side. The motive power in swimming is 

 obtained by a process of pumping, by which they are enabled to 

 fill the hinder parts of the body with water, and when they wish 

 to move with swiftness this water is, by a sort of piston, forced out 

 with a sudden j erk, which has the effect of propeUing the animal 

 forward ; thus its process is marked when swimming by a succes- 

 sion of rapid jerks. If it is lying near the surface of the water 

 when suddenly alarmed it will throw a jet of water for some 

 distance. 



Juli/ bth. 



Captain McDakin exhibited some Fossil wood from Folke- 

 stone, and made some observations thereon, of which an abstract 

 is given below. Mr. Dean introduced a variety of fresh water 

 objects, among which were some very beautiful specimens of 

 plumatella repens, which ho had obtained from a pond in the 

 neighbourhood, where a large cj^uantity of them had been ob- 

 tained during the last fortnight. Mr. Fullagar shoAved some 

 specimens of tho Melicorta ringcns, together with another 

 rotifer (Limnias ceratophylli), which he had lately discovered 



