12 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



uiinuto socondary setiferous tubercles, and it is difficult to distinguish the primaiT ones, whose 

 growth has become retarded or stationarj-, from the latter set, since thej- are so reduced in size. 



To enter more into details, while the tubercles of the anterior dorsal pair (fig. 1) in stage I 

 are already largo and much specialized, the integument crenulated or wrinkled, the seta finely 

 spinulated. while the long tubercle sends off a posterior tine or spur near the base; on the other 

 hand, the tubercles of the hinder pair {it) are minute in comparison and primitive in shape, the 

 tubercle itself a simple cone and the seta simple hair-like. Both sets of tubercles (/ and //) occur 

 on abdominal segments 8 and 9, the caudal horn on 8 being a highly modified tubercle /. The 

 same I'elations exist in stages II, III (figs. 2, 3, //). In stages IV and V, or the last instar. tubercles 

 ii are difficult to distinguish from the secondary ones, which are rather thickly crowded over the 

 dorsal surface; they can be distinguished on abdominal segment 8 directly behind and near the 

 base of the caudal horn. It mav be observed that all the thoracic and abdominal horns are in 

 Adelocephala hypertrophied tubercles /, and this will apply to the Ceratocampida? in general. 



In Si/-'ii!j}/un,>' niolina, stage I, tubercles ii are wanting on abdominal segments 1 to 7, though 

 present on segment 8 behind the caudal horn. This atrophy of // at once clearlj- indicates that 



Fig. 1. — Head and first five trunk-segu 

 arrangement o 



ents ot Sehizur 

 tubercles i-vii. 



this genus is a later, less primitive form than Adelocephala. a view corroborated by other 

 chanu'ters. 



In Kaden i/)i_periali.s, which, generally speaking, has evidently almost directly descended from 

 Adelocephala, the tubercles ii are absent in all the stages on abdominal segments 1 to 7. On 

 segment 8 the tubercles // are situated next to the caudal horn and are of good size in stages I, 

 II, and all the later stages, being about as large as tubercle /// on the side of the segment. 



In C'ltlu-rtmid reijHliii there are no tubei'cles ii on abdominal .segments 1 to 7. but they are in 

 stages I to V on segment 8. In stage I they are about one-half as large as the caudal horn itself. 

 In stages II and III (PI. LIV) they are large and branched, while in the last two stages they 

 become reduced, until in the final stage they are about as long as the caudal horn is thick at 

 its base. 



These tubercles (//) are jjresent on the eighth abdominal segment in V. Kepidcrali^ in all 

 stages; in C. xpleiidenx, stages IV and V (PL LV). and in the last stage of ('. hincoou (PI. LV). 



The species of Anisota form a side branch situated somewhat off' the main evolutional track, 

 having undergone a greater reduction of tubercles in the larval state and of the maxillw in the 

 imago than any of the other Ceratocampintu. Yet in Ilif tirst larval stage of each of the four 



