124 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY, 
“ Aussenlade” in Machilis, cannot be homologous with the part bearing 
the same name in other insects, for in Machilis it is clearly a part of the 
palpiger instead of being a constituent of the head of the maxilla. The 
two adductor muscles described by Oudemans (’88, Taf. I. Figur 19) 
as extending from the inner wall of the maxilla to a median tentorium, 
are probably the homologues of 3. and 6. pr’t. add. of Orchesella (Fol- 
som, 99, Plate 3, Figure 20). 
In CEcanthus, Ayers (’84, p. 241, Plate 18, Figures 20-22; Plate 19, 
Figure 5) has traced the development of the first and second maxillz as 
far as the trilobed condition, his ideas (p. 241) agreeing with mine on 
Anurida: “ The primitive appendage is first divided into two lobes, and 
the inner of these becomes secondarily divided into two.” Patten (’g4, 
p- 596) says, “A rather striking variation was found in the first and 
second maxille of Blatta, which were formed respectively of two and 
three lobes.” Wheeler (’89, p. 348) adds, regarding the same genus, 
“The outer of the three lobes of each maxilla becomes the palp, while the 
inner two become the galea and lacinia of the adult.” Heymons (95°, 
p- 19) states that in Forficula, “drei selbstandige Aeste zu erkennen 
sind, aus denen Lobus internus (lacinia), Lobus externus (galea) sowie 
der Palpus hervorgehen.” This trilobed stage is exactly comparable 
with that of Lepisma, although Heymons and Ayers differ as to its 
derivation. 
Although Wood-Mason (79) emphasizes the agreement between 
Machilis and Orthoptera, I may say that Lepisma is intermediate 
between the two in structure, with decidedly orthopteran affinities. 
Especially is this true of the first maxille. The cardo, stipes, galea, 
lacinia, and palpus of Lepisma (Muhr, *77, Taf. VII. Figur 45, or v. 
Stummer-Traunfels, ’91, Taf. II. Figur 11) not only agree in position 
with those of Blatta (Muhr, ’77, Taf. II. Figur 12, or Packard, 83%, 
Plate XXVIII. Figure 12, Periplaneta), but exhibit a surprising agree- 
ment in form, as well as the number of palpal segments ; in both groups, 
also, a palpifer is differentiated. Through Lepisma, therefore, the first 
maxille of Collembola may be homologized with those of Orthoptera, 
and hence all other Pterygote orders. I have traced the homologies, 
part for part, between Lepisma and all the families of Orthoptera, as 
well as the genera Ephemera, Myrmeleon, and Corydalus, in which lat- 
ter genera the nymphal first maxillee are but little specialized in form. 
Heymons (’96, p. 19) states that in the Libellulid genus Epitheca, 
‘“‘Erst spéter gliedert sich von der Aussenseite der Maxille eine kleine 
rundliche Erhebung ab, welche die Anlage des Tasters darstellt (Figur 
