44 MEMOIRS OF TIIK NATIONAL ACADEMY OF SCIENCES. 



coinpurutivoly small size of the clypeus. which i.s not .sunken Ix'low the level of the ej>icranium 

 a.s it is in the Syinhonihycina (eompare XLIV ligs. 10, 11. 12. with tius. 13 and 14). the clypeus 

 being still sniall(>r in Adelocephala than in the Heterocampime. 



As i'egai-(ls the armature, that of the notodontian groups Notodontinfe and Heterocampinaj 

 is closely similar to that of Ceratocampiiue. In neither group does more than a single seta arise 

 from a tubercle. 



In Schhnni cnnchtna (tig. 3) the tubercles are solid, chitinous, forming horns; the position 

 of the tubercles is in general much as in Adelocephala, but, as we should expect, the armatui'e 

 is moi-e primitive; tubercle /// is near the spiracle, /." moved up to a position just below and 

 behind the spiracle; while /' is quite remote, and vi nearl}' midway between /■ and /•//. Their 

 position, especially that of ///, //'. and /•, is the .same in Ilderocampa (jutth'itta, stage I, Seirodonta 

 l/ilinmta, and presumable in Notodontida? in general. On the other hand in the Ceratocampidaj 

 tuljerclcs Iv and v are united. The difference is a familv one, but this does not militate against 



ul lirsl iive trunk segments of Scfiiziir 

 arrangement of tubercles i-vii. 



the derivation l)y rai)id evolution (tachy genesis) of the more specialized or moditied Cerato- 

 canipin.e from the Notodontid.v, as it is now a matter of little doubt that evolution from one 

 .family or order or class to another may have in most cases at least been effected by a jump or 

 sudden mutation, without a long scries of connecting links. 



It should also be observed that in the Ileterocampiniv we htive the frequent concurrence of 

 "horns." i. e.. of the conversion of tubercles into solid chitinized horn-like processes, bearing a 

 seta at the end. While this may be a .sporadic specialization of the dor.sal tubercles of stage I of 

 from only one ])air (prothoracic in //. hlundata and If. unicolor) to as many as .seven (//! ohViqua) 

 and nine (//. (jutlir'iitd)., yet it is not without .signiticanee. as pointing to the evolution of a group 

 like the CeratocampidiT?, where they are retained throughout larval life. 



Here the question arises whether these antlers and spines of Heterocanqia anil the reduced 

 prothoracic horns of Mdcrurocaiupa inarthesia and of ('crura may not have i)een handed down 

 from the genus Schizura, or at least that section of it. or the incipient genus represented by 

 S. cniciiiii'i. in which all the segments bear tubercles (/). which have liecome specialized into 

 stout spines. 



While the pupa of Ileterocampa resembles that of Eacles in the general shape of the head- 

 region, and in having a forked cremaster. what appears to be a difference of family importance 

 is seen in the two promintMit divisions of the lower jxirt of tht> front of the head, representing 

 the clypeus and hibiuin. 



