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this structure in the Bombycidse and the groups placed between them 

 and the Rhopalocera. In the Hesperidae, the males, so far as I have 

 examined them, have the supra-anal plate small, lunate or crescent 

 shaped, there is no supra-anal hook, and the side pieces are short, and 

 illy, or not at all adapted for clasping. Some, perhaps many of the 

 higher groups have the supra-anal plate well developed, but it is with 

 the lowest of the group — those placed at the end of the series, that 1 

 have now to deal. 



Among the Heterocera the ZygacniJae most nearly approach the 

 Hespcriihie in this respect; entirely lacking the supra anal plate, and hav- 

 ing the side pieces scarcely modified into clasping organs. 



The SyiiiomiJae are closely allied in structure; but here, though the 

 supra-anal hook is not, in the forms examined by me, fully developed, 

 it is well indicated, and the side pieces are often corneous and furcate, or 

 provided with separate corneous claspers. In Didasyi these organs are 

 very prominent and furnished with long tufts of hair. 



Allied to the Synioinidae are the Aegeridae, or Sesiidae as some 

 prefer to call them. But here the supra-anal plate undergoes a modifi- 

 cation: instead of being solid, a triangular space is punched out of the 

 center, leaving a triangle with its apex somewhat dilated. There is no 

 supra-anal hook in those specimens examined by me, and the side piece 

 is simple. 



In the Macroglossae another peculiar modification appears. Here 

 the plate is narrowed, thickened and takes i. shape somewhat like a 

 Lobster's claw. The side piece is simjde, and there is a stout, straight, 

 corneous spine below the intromittent organ. 



Sphinx has usually a complete supra-anal plate and hook, and 

 often corneous claspers. 



In the higher Bombycidae we notice a curious and remarkably con- 

 stant modification — the supra-anal plate is present though often much 

 reduced in size, and the tip is somewhat prolonged, but instead of 

 forming a spine it divides and forms points, or lobes, varying in the 

 species. I illustrate ytiihia, cecropia, regalis, imperialis and Adelocephala 

 bicolor and all the other large species examined by me, present the 

 same form.* 



This modification gradually runs into the normal form; but through 

 what stages it passes to do so I am not yet prepared to say. 



Little as I have done yet, the results attained are still instructive — 

 in combination with wing structure and habits they suggest a classification 

 somewhat diflerent from that usually adopted. 



The Syntomidac with diurnal habits, clear, bright or contrastingly 

 * Figures of these peculiarities will be presented at a future date.— J.B-S. 



