tffihe Mole-cricket. il9 



caslon, ill the mode supposed to be employed. Even in the for- 

 mation ot" mineral crj'Stals, which are unorganized bodies, the 

 attraction by which the component particles are aggregated is 

 regulated by laws the most systematically framed and observed: 

 and whoever has viewed with any attention that wonderful mo- 

 nument of human industry and sagacity, theAnatomicalMuseum 

 of John Hunter, and has there seen the proofs of a sangui- 

 neous circulation in animals of an order so low that they can 

 hardly be said to have any specific form or substance, will al- 

 most necessarily be disposed to expect a similar provision in 

 a class of animals whose general structure is so elaborately 

 and beautifully organized as that of insects. But I shall again 

 advert to this subject after having described the tracheal sy- 

 stem or respiratory organs of the insect under consideration. 



The oyga?is of respiration. — As it is very generally known 

 that the atmospherical air, so necessary for the existence of 

 all animated beings, is admitted into the bodies of insects by 

 certain apertures called stigmata, and is then distributed 

 through the system by means of tracheae or air-tubes, I shall 

 not dwell longer on the description of those organs in the 

 gryllotalpa than is necessary for the elucidation of its particu- 

 lar history. 



Omitting the questionable existence of two stigmata in the 

 upper lip, and of two others in the vicinity of the caudal an- 

 tennae, there are ten stigmata very distinctly visible on each 

 side of the body*. Hence, therefore, it is necessary to cor- 

 rect (though probably it has ere this been corrected by him- 

 self) a statement made by Cuvier in his Regne Animal, tom. iii. 

 p. 126, that in the Myriapoda there are twenty stigmata and 

 upwards, but in all other insects eighteen at most. He also 

 asserts in the same place, that insects respire by two principal 

 tracheae extending longitudinally, one on each side of the body, 

 from which other tracheae ramify. Now certainly in the gryl- 

 lotalpa, and, as I have reason to believe, in many other insects 

 also, the longitudinal tracheae bear so small a proportion in 

 their capacity to the aggregate capacity of the other ti'acheae, 

 that in such instances they cannot be called principal tracheae. 

 My own opinion is, that these longitudinal tracheae serve as 

 connecting channels, by which the insect is enabled to direct 

 the air to particular parts, for occasional purposes. 



Though not immediately bearing on the present point, I 

 beg leave here to state a fact which I have not seen elsewhere 

 noticed; that in the two segments of the body which carry the 

 middle and hind pair of the true legs, in the larvae of coleop- 



•VidcPhitell. fij;. 10. 



