14 



2. Smooth, subspherical warts (Zi/gaenidae e. g. Chalcosia, East 

 Indies) or elongated but still smooth {Attacus atlas and a species 

 from South-western territories U. S. A.). 



3. Subspherical or clavate, spiny tubercles of many Attaci, 

 the spinules usually short. 



4. Spinulated spines or elongated tubercles of Ceratocampidae 

 and Hemilucidae {H. io and H. maia etc.). 



5. Spikelike hairs or spines (Samia cynthia, Anisota, East-Indian 

 Hypsa, Anagnia). 



6. Antler-like spines. Early stages of Heterocampa biundata, 

 (juttivitta and obliqua. 



B. Hetae (^hairs", bristles etc.). 



1. Simple, fine, short or long, microscopic or macroscopic setae, 

 tapering hairs, scattered or dense, often forming pencils (Many 

 Bombyces, Zygaenidae, Noctuobombyces, Apatelae). 



2. Glandular hairs, truncate, spindle-shaped or forked at the 

 end and secreting a more or less viscid fluid (Many in stage I 

 and II of Notodontians, many butterfly-larvae and in the last 

 stages of Pterophoridae). 



3. Long, spindle-shaped hairs of Apatelodes, Apatela americana, 

 and the European Tinolius eburneigutta Walk. 



4. Flattened, triangular hairs in the tufts or on the sides of 

 the body of Gastropacha americana, or flattened, spindle-shaped 

 scales in the European G. quercifolia. 



5. Spinulated or barbed hairs. Most Glaucopides^ etc. Arctians, 

 Lithosians and lAiJaridae and many other Bombyces. 



C. Pseudo-tubercles. 



1. The filamental anal legs (stemapoda) of Cerura and Hetero- 

 campa morthesia. 



2. The long suranal spine of Platyptericidae." 



Packard's view on the origin of these different forms is the 

 following (1890 1. c. p. 560) : 



1. The more prominent tubercles and spines or bristles arising 



