ME.MOIKS OF THE NATIONAL ACADEMY OF SCIENCES. 135 



foregoing' description h:is been drawn up from four well-preserved alcoholic specimens and a 

 blown one. 



This larva differs generically from Eacles in having well-developed dorsal spines on the 

 prothoracic segment, while the lateral ones along the abdominal region are also well developed, 

 these being nearly obsolete in Eacles. The genus Citheronia is unique in having 7 spines on the 

 eighth and the ninth abdominal segments, respectively. AH these characters are seen to be 

 secondary' and adaptive, and yet they are good generic charactei's, showing that the acquirement 

 or loss of generic characters is due to adaptations to the surroundings. The specific characters 

 are well brought out by comparing C. regalln and C. sepulcraUs. 



KECAPITULATIOX OF THE SALIENT FEATURES IX THE ONTOGENY OF CITHERONIA KEGALIS. 



A. — Congi-nttal chantctcrs of the larva, as seen hi stage I. 



1. The three pairs of enormous spines, the first or prothoracic pair but little shorter than 

 the third, and the middle pair about two-thirds as long as the body, all ending in a swollen, 

 triangular, two-horned flattened bulb; these appendages l)eing deterrent and for oflensive use in 

 the earliest as well as latest larval life. 



2. Both the eighth and ninth abdominal segments bearing a high median dorsal horn, and 

 these segments bearing 7, instead of only 5, spines. 



3. The lateral spines on the abdominal segments nearly as large as the dorsal ones. 



4. Bod}' dark; head dark in color. 



B. — Eiyilution of later adaj/tat/'onal e/mracters. 



1. The bulbous tips of the thoracic horns dropped at the end of stage II. 

 •2. The thoracic horns become curved in stage II or III. 



?>. The thoracic dorsal spines become much stouter, with nuich shorter and stouter spinules 

 at the last molt. 



4. The mature larval features mostly assumed in stage III. 



5. The dark colors exchanged after the last molt for pale green, with bluish tints. 



6. The black dorsal thoracic spots and the lateral yellowish bands most showy in the last stage. 

 ,A.ttention should be drawn to the colossal size of this larva, as compared with that of 



Adelocephala and even Eacles, though the head is not so much larger. This is due, perhaps, to 

 its sluggish life, greater digestive and assimilative powers, so that a rapid acceleration of the 

 growth of the body takes place; owing to its protection from the attacks of birds, it may feed 

 openly and continuously. It is thus similar to sphingid and attacine larvK in its huge body and 

 enormous appetite. The largest cochliopod larva; are the spiny ones, and the spiny or 

 tuberculated Saturnians and Attacinse have thick, large bodies. 



PajKt.—P\. LVI, fig. 7; PL XXXV, figs. 2, 2a, 2h. 1 9 . Body thick, head well rounded: body 

 smooth, with no such spines as in Eacles either on the head, thorax, or abdomen. Themaxilhe long, 

 though a little shorter than in Eacles; these, as well as the parts of the head in front, and the legs, are 

 more convex on the surface than in Eacles. Antennie slightly narrower and smaller than in 9 

 Eacles. The abdominal segments smooth on the hinder edge, there being little pits instead of low 

 spines. End of the abdomen very blunt and rounded, the cremaster reduced to a vestige not so long 

 as broad, irregularly conical, with two short thick divergent tubercles at the end. No spines 

 on the foi'e or hinder end of the abdominal segments. 



Length, $, 60 mm.: thickness, 23 nun. 



Food jjlants. — Black walnut, butternut, hickory, persimmon, sumach, sweet gum, sycamore, 

 and ash. Found on the lilac in St. Louis (Kern ex Ililev). 



Destroyed a considerable number of cotton plants in Natchitoches, La., in September, 1890 

 (Riley); did considerable damage to sea-island cotton in Bradford County, Fla., 1891 (Riley). 



Odor (f the papa and moth. — Riley states: ''Both the chrysalis and the moth have 

 a characteristic strong odor which can not easily be described for lack of comparison, though it 



