LEE BARKER WALTON 7 



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 seg- 

 ments."^ In addition to ecdysis, insisted upon by Bordage,^ 

 we must take into consideration various other selective 

 factors, chief among which appear to have been mutila- 

 tions by enemies. The severing of the segments, which 

 resulted from either factor, would probably 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 

 polypodial forms that a series of the appendages move 

 more or less in unison, and it is obvious that such rhythmic 

 motion is better maintained with the articulation of a 

 coxa and trochanter alone than with an additional articu- 

 lation between the trochanter and femur. This may be a 

 factor in accounting for the more pronounced fusion of 

 the two segments in the Diplopoda. 



In 1893 Hansen^ endeavored to homologize the 

 trochanter of the Hexapoda with the ischiopodite in 

 Crustacea. This homology was based on the supposition 

 that the part assumed by him to be the trochantin* in the 

 Cicadaria (Cicadid^, Fulgoridse, Cixidie, etc.) was the 

 homologue of the coxopodite in Crustacea. In referring 

 to Machilis, he has considered the trochantin of the 

 prothoracic coxa as a primary segment, homologous with 

 the coxopodite. From comparisons, however, with both 

 Chilopoda and Diplopoda, we would regard the trochantin 

 rather as a specialized character of the Hexapoda, which 



I have adopted the translation as given by Austen. 



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 me- 

 chanical 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 endeavored 

 to show, seems unwarranted. 



Zur Morphologic der Gliedmassen und Mundtheile bei Crustaceen und Insecten. 

 Zool. Anz., pp. 193-198, 201-212, 1893. 



It seems probable that Hansen has here applied the name "trochantin" to the 

 antecoxal piece and trochantin together. 



