Affinities of Pteronarcys regalis. 433 



places. This also appears to be the habit of other species of the genus as 

 well as of Pteronarcys regalis. Mr. Gosse, who first figured the latter spe- 

 cies in his ' Canadian Naturalist,' informs me that he has taken P. Proteus 

 and another smaller species in Lower Canada, at Sherbrooke, where the 

 Magog river forms a waterfall of considerable height, on the rocky sides of 

 which, constantly washed by the spray, he has found P. Proteus in great num- 

 bers, hanging to the sides, or concealed in the crevices of stones and rocks, 

 and that he has but very rarely taken it on the banks of other parts of the 

 river. The Pteronarcys thus resembles an amphibious animal in its habit of 

 life, and may be designated, — if 1 may be allowed the term, — an Insect Proteus 

 among the winged Articulata, — the representative in structure, as it appears 

 to be in habit, of the Proteus of Vertebrata. Its organs of respiration fully 

 justify us in instituting this comparison. The true Proteus has both lungs and 

 branchiae, and a similar conformation of structure exists in Pteronarcys, in so 

 far as the ramified tracheae being the direct recipients of atmospheric air, are 

 to be regarded as the representatives of lungs. 



Sternal Orifices and Endo-skeleton. — In the short notice which I formerly 

 published on this singular insect *, I pointed out the existence of three pairs 

 of orifices in the tegument of the sternal surface of the thoracic segments 

 {fig.bf,g,h), one pair in each segment, between the insertions of the legs, 

 precisely analogous in situation to the respiratory orifices in lulus and some 

 other Myriapoda. But as these orifices had not then been traced to their 

 termination within the body, and as their situation in the segments was of 

 doubtful indication in a hexapod insect, no conclusion could be drawn from 

 the mere fact of their existence as to whether they had or had not any com- 

 munication with the tracheae. I have now examined them carefully, and find 

 that they pass into the thorax as strong, bone-like tubes, diverging from the 

 axis to the periphery of the body, in the immediate vicinity of some of the 

 principal tracheae, but that they do not in any way communicate with them, 

 as they terminate abruptly as caecal structures. They are, in fact, intus- 

 suscepted parts of the hardened tegument, — organs of support, — which in most 

 other insects are solid. They are the ento-thoracic portions of the sternal 

 plates in each segment (fig. 14), the ante-furca (u), meso-furca {v), and meta- 



* Annals aod Magazine of Natural History, Jan. 1844, p. 23. 

 3 l2 



