MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 43 



Thvatira-liUo noftuid. may have very soon after tlicir establishment become split by diveiyi iit 

 evolutionary forces into two jiroiips. one giving rise to the Syssphingina and the other to the 

 Symlioinln'cina. As will be seen by oui- i)ro\isional, tentative, phylogonetie diagram, the more 

 primitive notodontians. i. e., those which at birth are armed with simple setiferous tubercles, 

 gave rise to the Syssphingina. 



The other branch or group of Notodontida". in which the larva on hatching is armed with 

 multisetose warts, gave rise through Ichthyura to the superfaniily Syml)oml)ycina, which com- 

 prises the six families alrea(iy mentioned. 



The Eurypterotidiv may have descended from the Apatelodiiiie. I have; not recently studied 

 this group and follow the suggestions of Dyar, who states that ApatAodcn tonvfacta in its first 

 stages distinctly shows the wart characters of the Eurypterotidiv. 



In the case of the position assigned to the Liparida- (Lymantiiidie) and Lasiocampida^ I 

 follow in the main the suggestions of Dyar, having at present nothing new to offer. 



From the statements of Grote, and my own observations on the nature and position of the 

 warts of the freshly hatched larva of Bomhi/.r mor! and an investigation of its later stages, also 

 from an examination of the fully grown larva and the pupa of EnJromw versicolora^ as well as 

 recent studies on Brahmxa japonica, I have satisfied myself that the superfaniily Synibombycina 

 ends in a group of three specialized families, as represented in the diagram on page -Ki, which have 

 all apparently descended from some common type. All have multisetose warts in stage I, and 

 lose them after the Krst molt; all have a caudal horn, while the Brahma^ida> have thoracic and 

 hinder abdominal horns in stages H-IV. The P2ndromida> and Bonibycidw appear to have 

 branched oft' from a common stem-form, which had four medic-cubital branches. The Bombycidie 

 underwent a process of degeneration: losing a vein, the head becoming reduced in size, the 

 palpi much reduced or absent, the maxilhe completely lost, the wings narrow and the power of 

 flight weak, the frenulum absent, the legs being spurless. 



The most aberrant and specialized group is the Brahnuvida>, which we shall elsewhere treat 

 of at greater length. It is to he ohservt-d that in these fain ilivs what are the larval characters of 

 the last stage of hairy notodontians and the families directly related to them have heen a'owded 

 hack during the coarse of their phylogenetic evolution, and are confined to stage las the result cf 

 the atrophy of the multisetose ivarts; the body after the first molt becoming naked and the caudal 

 hump or horn becoming a conspicuous feature, though even this is lost in the final molt of Brah- 

 mfea. It is interesting to observe in the ontogeny of Braitimra jajxmica that before the first 

 molt, besides the ordinary multisetose warts those of the second and third thoracic and the eighth 

 and tenth abdominal segments are greatl.v elongated and hypertrophied, with the fine spinulose 

 slender seta? scattered along the trunk and at the end. These horn-like processes are, however, 

 discarded at the last ecdysis, when the body becomes naked, with mere vestiges of the '• horns" left 

 to tell the tale of descent from some form more specialized in stage I than any other of the super- 

 family y(>t known. 



It should be observed of the families embraced in the Synibombycina, that they are all 

 Asiatic and African forms; i. e., Arctogteic (chiefly inhabiting the oriental region) and Ethiopian. 

 The Apatelodina', on the contrary, which we may provisionally regard as the stem form of the 

 Eurypterotida'. is American, the species all being confined to Central and North America, though 

 A. ardeola Druce ranges from Panama to the Amazons. 



It seems not impr<)i)able that the genus originated in Neogala, gi-adually passing northward 

 into the eastern Mexican and Atlantic regions of Arctog»a. Whether the ultimate origin of 

 such a great family as the oriental one of the Eupterotida' was in South America seems some- 

 what problematical. 



Origin of tlie suprrfiinll y Syssphingina. — The proofs of the more or less direct origin of 

 the Ceratocampid;e, and especially the genera Adelocephala and Syssphinx from the more primi- 

 tive Notodontida>; i. e., those with larval unisetose tubercles, seems very strong. The affinities 

 of the larv;e of the two groups are seen in the shape of the head, the long high epicranium. nar- 

 rowing towards the vertex, the great length of the median suture of the epicranium, and the 



