Miscellaneous. 447 



or coherent reticulate skeleton," while with the latter were associated 

 types in which the skeleton consisted of " isolated or loosely inter- 

 woven spicules " only. Zittel, as I find by reference to a copy of 

 his original essay, with which he has kindly furnished me, makes it 

 accidentally read exactly the reverse. In my original diagnosis 

 (I. c. p. 252) I further proposed to characterize the group of the 

 " Calicispongice " as possessing spicule-protected gemmules instead 

 of both having " naked membranous gemmnles " as rendered by Prof. 

 Zittel, 



W. Saville Kent. 

 4 Marine TeiTace, St. Heliers, Jersey, 

 Oct. 17, 1877. 



Phenomena accompanying the Metamorphosis of Libellula depressa. 

 By M. JoussET DE Bellesme. 



The author gives an extraordinary account of the mode in which 

 Lihellida depressa expands to its full size and extends its wings 

 after quitting the pupa-skin. After describing the well-known pro- 

 cess of the emergence of the insect, he inquires by what mechanism 

 does the insect inflate itself and increase its volume to such an 

 extent that after issuing from its little envelope it suddenly becomes 

 double its former size. 



He states that at this time the function of respiration, which 

 is very active in the adult dragonfly, is not yet set up. There are 

 no movements of inspiration and expiration ; the abdomen is cjiin- 

 drical ; and the deep fold in the ventral surface of the abdomen, 

 which he regards as essential to respiration, is not yet in existence. 

 On dissection the air- sacs of the body are found to be empty and 

 flaccid. 



Nevertheless the inflation of the dragonflj^ is eff'ected by air ; and 

 if the body is cut through with a pair of scissors it collapses in a 

 moment like a balloon. By taking suitable precautions and dissect- 

 ing the animal under water, it is found, he says, that the digestive 

 tube here performs a most unusual physiological part. It is so much 

 distended that it absolutely fills the whole interior of the body, 

 pushing the other organs against the integuments. Under the in- 

 fluence of this energetic pressure the blood is jiressed forcibly to- 

 wards, the pei'iphery, distends the eyes, and gives the head its 

 definitive form ; then passing into the wing, between the two mem- 

 branes, which up to this time are separate, as M. Blanchard has 

 described them, it accumulates in the wing, unfolds it. and circulates 

 in it, depositing- the pigment which is destined to colour it. During 

 this time the integuments, which are distended and bathed by the 

 nutritive fluid, acquire their proper colour and solidity. It is by 

 swallowing the air and storing it in its digestive tube, says the 

 author, that the Libellula obtains the force necessary for the accom- 

 plishment of most of its transformations ; and he thinks there is 

 every reason to believe that the same thing occurs in many other 

 insects. — Gomptes Rendus, August 20, 1877, p. 448. 



