NATURAL SCIENCES OF PHILADELPHIA. 383 



quently the case that the anterior femora possess a confluent inferior and 

 anterior, while the other four femora have merely an inferior. Further varia- 

 tions between different species are caused by the vittae being abbreviated. As 

 a general rule, in Agrionina, each pair of legs is darker than the pair imme- 

 diately behind, them, when there is any difference ; but in JEschnina and 

 Libellulina the contrary rule seems to prevail. The colorization of the tibiae 

 and tarsi, as compared with that of the femora, is simple ; they have merely 

 an inferior vitta, whose locus is rather on the anterior row of spines, and a 

 superior vitta. 



Why, if every separate species of Gomphus and Agrion had been separately 

 created, the great Author of Nature should have thus restricted himself to 

 working upon one pattern only a phenomenon which has been noticed in 

 many other families of insects, as, for example, in Cicindelidae, by my friend, 

 Dr. J. L. Le Conte is to me an insoluble problem. Why do we never find 

 odonates with their legs fasciate, instead of vittate ? On Mr. Darwin's 

 theory, the reason becomes at once apparent. In Macrogomphus? spiniceps 

 mihi I have recorded a remarkable apparent deviation from the unity of color- 

 ization elsewhere observable in the thorax of Gomphus ; but I am convinced 

 it is only apparent. 



Another point in which I have deviated from the nomenclature of Dr. Hag<n 

 and M. Selys is in some of the pieces of the head. The front of the odonatons 

 head or, as Say calls it, in (csch)ia and libellula, "the frontal vesicle," as dis- 

 tinguished from "the vertical vesicle" is divided into two subequal parts by 

 a transverse suture or stria, below which comes another shorter and generally 

 curvilinear transverse suture, which separates what agreeably to the analogy 

 of other orders I call the epistoma, it being the piece immediately overlying 

 the labrum, with which it is connected by a more or less membranous suture. 

 The authors of the Monographic call this last piece "the rhinarium," and the 

 lower part of what I consider to be the front they call " the nasus," or some- 

 times "the epistoma," confining the term "front" to that part of Say's 

 "frontal vesicle" which lies above their "nasus." I am by no means certain 

 but what their "nasus" and "rhinarium," taken together, are the analogues 

 of what in other orders is called the epistoma; but their "nasus" by itself 

 can scarcely be so. 



Calopteryx maculata, Beauvois. (North and South Illinois.) 



Het.erina rupinsulensis, n. sp. <$ Black, with a slight brassy tinge. Head 

 hairy, pale brown in front of a transverse line passing behind the base of the 

 antenna? ; labrum with a lateral black tubercle ; mandibles and the tip of the 

 labium brown-black ; all beneath pale-brown ; post-occipital tubercles promi- 

 nent, acute ; antenme with their first and second joints pale brown ; and the 

 third, which is longer than the first and second put together, black ; the seta, 

 which is shorter than the third joint, black. Thorax hairy ; prothorax with 

 a large triangular posterior lobe ; dorsum of thorax with a brown lateral 

 stripe, becoming much wider inside on its terminal half; pleura pale 

 brown, the anterior half of its anterior segment with an abbreviated black 

 stripe pointed above, the posterior half with a rather narrower one, abbre- 

 viated above and below, not attaining the spiracle which is black ; a short 

 black line above in the suture between the two segments ; the posterior seg- 

 ment with a much abbreviated black stripe, the narrowest of the three ; 

 sternum pale brown. Abdomen with an obscure yellowish lateral stripe, 

 fading out at the end of the third segment ; joints 1 2 hairy, the two or three 

 terminal joints pubescent under the lens ; joint 2 brown on its basal two- 

 thirds ; 2 7 with an obscure yellowish basal annulus, more obvious on 3 5 ; 

 a carina on the tip of joint 10, terminating in a spine, with a small spine on 

 each side ; joints 8 10 each one-third shorter than the preceding joint ; venter 

 black, with a polished longitudinal tubercle on the tip of the last segment, 

 immediately behind the insertion of each lower appendage. Superior ap- 



1862.] 



