268 THE AMERICAN NATURALIST. | [Vor. XXXIV. 
is in many cases entirely absent, it is evident that it is a 
characteristic of a primitive stem form, and has not arisen, as 
Bordage suggests, from an “ancestral form belonging to the 
existing Phasmids in which there was a distinct articulation 
between the two consecutive segments."! In addition to 
ecdysis, insisted upon by Bordage,? we must take into consid- 
eration various other selective factors, chief among which 
appear to have been mutilations by enemies. The severing of 
the segments, which resulted from either factor, would prob- 
Fic. 1. Metathorax ; c, coxa genuina; m, n; eps, —: epm, 
epimeron ; a, antecoxal piece; s, sternum; £ (?), Micuidbi 7 wienn J, femur 
ably occur near the base of the appendage, and the favored 
forms would be those in which the two segments were 
approaching the fused condition, the invagination of the 
chitinous wall preventing undue hemorrhage. Autotomy, 
"which Bordage so fully explains, would undoubtedly play an 
important part here. It also appears advantageous to poly- 
1] have adopted the translation as given by Austen. 
2 The position of Bordage in regard to the manner in which the fusion has 
come about is clearly on the side of Neo-Lamarckianism, since he attributes it to 
* a mechanical strain," and says that it is an “example of a character acquired by 
use...and then transmitted by heredity.” This conclusion, however, as I have 
BENEAT to show, seems unwarranted, 
