24 Mr. G. Newport on the existence of Bronchia in Pteronarcys. 



distinctly show this to be the case, and also have reference to the 

 apparently anomalous persistence of branchiae as respiratory or- 

 gans in Pteronarcys. Mr. Westwood in his ' Modern Classi- 

 fication of Insects*^ has quoted, as a remarkable circumstance 

 connected with the respiration of the SialidcP, an observation made 

 by M. Pictet, "that one of these larvse lived fifteen days in the 

 earth before it changed to the pupa, being," he remarks, " the 

 only instance of an insect furnished with external respiratory or- 

 gans respiring the ordinary atmospheric air." I cannot perceive, 

 however, what our worthy friend, or M. Pictet, from whom he 

 quotes the fact, has discovered so exceedingly wonderful in this 

 circumstance. There is nothing more remarkable in this fact, 

 than in that of the common caterpillar of the Sphinx remaining 

 unchanged in its cell in moist earth for many days before it 

 enters the pupa state. The truth is, that as the period of change 

 approaches, the respiration of the larva is reduced to its minimum, 

 and is almost entirely suspended ; consequently the medium in 

 which the insect is placed, whether it be water, or air saturated with 

 that fluid, as it necessarily must be in a cell of moist eai'th, is as 

 well fitted for branchial respiration as water itself. That the 

 functions of branchiae are fulfilled under tlicse circumstances, 

 I need but, in proof, direct attention to the known fact that 

 Crustacea will continue to respire in the open air for an indefinite 

 length of time, so long as their branchiae are kept moist by fluid 

 retained beneath the folds of the thorax. In closing these re- 

 marks I again refer to the question, have the habits of Ptero- 

 narcys any reference to the branchial structures in the perfect 

 insect ? My own opinion inclines strongly to the aflirmative. 

 The Pteronarcys shun the ojien day, during which they remain 

 secluded beneath stones or in damp places, where the air is 

 charged with moisture. They come abroad at night, and are con- 

 stantly in the neighbourhood of streams and rivers, in which lo- 

 calities also the air is saturated vAi\\ moisture. Under either of 

 these circumstances the branchiae may be sufficient for all the 

 purposes of aeratioi>. 



I may also further observe, that branchiae appear to be a well- 

 marked generic character of these insects, although hitherto over- 

 looked. In the dried specimens they become shrivelled, and are 

 almost lost ; but I have had the satisfaction of detecting the re- 

 mains of them in the original specimens described by Mr. New- 

 man, and now in the collection of the Entomological Club. They 

 are in so shrivelled a condition as to have been easily overlooked ; 

 and would not, probably, have at all been recognised were they 

 not fii'st seen in this recent and well-preserved specimen in spiritf. 



* Vol. ii. p. 50, note. 



\ The sppfimcu preserved by Mr. Biinistone ia spirit was exhibited at 

 the nicctinc:. 



