196 A Classification of Lejjidojyteroiis Larvae. 



is the same in all stages. These larvte rarely have more than five 

 stages. In the second, represented by the Arctiid^ and Lymautri- 

 idae, and by many Butterflies, the first larval stage is remarkably 

 different from the following ones. In these embryonic larvae, which 

 have not passed a moult since leaving the egg, we find a generalized 

 condition of the tubercles and set®. I have concluded not to con- 

 sider the larvag in their first stage for this reason, the more so as it 

 is doubtful if the character of the presence or absence of this gener- 

 alized first stage has any special phylogenetic significance. It would 

 seem, rather, to depend upon the necessity of shortening the larval 

 stages, or upon the condition of the environment of the individual, 

 which rendered it necessary for the little larva to come into active 

 existence fully armed, as is the case with the newly hatched larvas 

 of Heterocampa and Cerura among the Notodontidae or with the 

 Sphingidae. Others, with less necessity for an active struggle in 

 very early life, have retained the primitive or generalized condition 

 till the first molt. 



The Arrangement of the Tubercles. 



There are two types of arrangement. The first, which is by far 

 the more generalized, consists (considering only the abdominal seg- 

 ments) of five tubercles above the spiracle on each side, three in a 

 transverse row about the middle of the segment and two behind ; 

 below the spiracle are two oblique rows, containing, respectively, 

 two and four tubercles. This type is found in Ilepialus, and is 

 probably typical of the larvae of the moths in Prof. Comstock's first 

 suborder, the Jugatae.^ 



The second type contains two dissimilar lines of modification of 

 the first type ; but, as they agree in number of tubercles and in 

 other characters, I will consider them together. The fundamental 

 arrangement of the tubercles is as follows : On each side above the 

 spiracle three tubercles; below, or behind the spiracle and above the 

 base of the leg, three more ; on the base of the leg three (or four) 

 on the outside and one on the inside near the midventral line. 

 These I propose to designate thus, counting from the dorsal line 

 down the side: Tubercles i, ii, iii above the spiracle, iv, v. vi below 

 it ; the group of three on the outside of the leg as vii, and the single 

 one on the inside of the leg as viii. Tubercles vii and viii are present 



• I have not had Micropteryx for examination. 



