MK.MOIHS OF THE NATIONAL ACADEMY OF SCIENCF:S. 135 



forocvoint;' description bus hccn drawn u[) lioni four wcll-iiri'scrved alcoliolic specimens and a 

 blown one. 



This larva diti'ers <i-enericaily from Eticles in has inj^- well-developed dorsal spines on llic 

 prothoraeie seyiiient. while the later:d ones aloiiy" the uhdoniinal region are also well develoi)ed, 

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

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

 secondary and adaptive, and yet they are good generic characters, showing that the acciuiivmcTit 

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

 are well brought out by comparing C. regalU and C. aepulcralis. 



RECAPITLLATIOX OF THE SAI.IIZNT FEATURES IX THE (1NTOGENY OF CITHERONIA REGALIS. 



A. — Co)i</<n!ttd characters! <rf the /arrn. (is xtcii In stage I. 



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

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

 triangular, two-horned flattened bulb; these appendages l)eing deteri-ent and for offensive 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 l)earing 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. — Ecolntion of latt-r adaptational characters. 



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. 



3. The thoracic dorsal spines become much stouter, with much 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. 

 Attention should be drawn to the colossal size of this larva, as compared with that of 



Adelocephala and even Eaeles, 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 larvte 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. 



P«j!M.— PI. LVI, tig. 7; PI. XXXV, tigs. 2, 2fl, -Ih. 1 9 . Body thick, head well rounded: body 

 smooth, with no such spines as in Eaeles either on the head, thorax, or abdomen. The ma.xiihe long, 

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

 more convex on the surface than in Eaeles. Antenn;e slightly narrower and smaller than in ? 

 Eaeles. 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 fore or hinder end of the abdominal segments. 



Length, 9 , 60 mm.; thickness, 23 mm. 



Food plants. — Black walnut, l)utternut. hickory, persimmon, sumach, sweet gum, sycamore, 

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



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 of the pupa 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 



