﻿NORTH AMERICAN SPHINGIDiE. 123 



abundantly distributed, and which are either continued from one side to the other, or 

 project into the interior as loops. I think the former is the case, yet I have an im- 

 pression that I have seen loops on the inner surface, but in any event, the interior 

 space serves to receive a large number of unprotected or free tracheal tubes. These 

 arise almost erectly from the interior surface, seeming to pierce the chitinic walls. 

 From these peculiarities of structure, I imagine their physiological function to be 

 connected with the aeration of the circulating fluids. 



The Patagia or the vesicular-like enlargements found on the dorsum of the pro- 

 thorax of lepidoptera, have the same internal structure as the tegulse, and communi- 

 cate with the interior by openings or foramina. They are, indeed, simply folds of 

 the prothorax on the dorsal surface, and are either fibrous or partially hardened by 

 the deposition of chinitic matter. The prothoracic spiracle is placed between the lateral 

 patagia and the base of one of the tegula. The mesothoracic and metathoracic seg- 

 ments are unprovided with spiracles, as in the embryonic state, but their analogues 

 are found in the openings through which the tracheal vessels are distributed to the 

 wings. 



I cannot close this article without first making a few personal acknowledgments. 

 I am indebted for many acts of disinterested kindness, and for much assistance in 

 various ways, to my friend Mr. Samuel H. Scudder, Jr., of Boston, a pupil of Prof. 

 Agassiz. He is, at the present time, engaged in collecting materials for a monograph 

 of the family Hesperidse, and those into whose hands this article may fall, will aid 

 the development of entomological science in America, by contributing such specimens 

 as their collections may contain, should he desire aid of this kind. They will be 

 returned cheerfully after having been fully examined, should the contributor desire it. 

 All such contributions, however, should be sent to the student with the expe-nses pre- 

 paid. The expenditures which the student is obliged to incur, are sufficiently onerous 

 without being taxed in this manner, and are insignificant to each individual contribu- 

 tor. I trust there are but few entomologists or collectors in the United States, who 

 would themselves display or encourage in others, that entomological selfishness 

 respecting specimens, which induces the possessor of what is rare or difficult to obtain, 

 to guard it with jealous and puerile exclusiveness, when so much must be done by 

 the special student, to place lepidopterology with us in a condition of usefulness. An 

 unstudied and unsystemized collection, has no value even to the possessor himself 

 when it is not used for the advancement of science, and it would be quite as 

 creditable, and quite as sensible, to devote time to forming a collection of curiously 

 constructed horseshoes or any other objects, as to make one of insects, if the col- 

 lector accumulates for the satisfaction given by the display, and pleasure of keeping- 

 it for himself and friends to gaze at and vapidly wonder over. 



My acknowledgments are also due to Messrs. W. H. Edwards, of Newburgh, N.Y., 



