124 BULLETIN: MUSEUM OF COMPAKATIVE ZOOLOGY. 



" Aussenlade " in Machilis, cannot be homologous with the part bearino- 

 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. Fi^'ur 19) 

 as extending from the inner wall of the maxilla to a median tentorium, 

 are probably the homologues of 5. and 6. 2ir't. add. of Orchesella (Fol- 

 som, '99, Plate 3, Figure 20). 



In (Ecanthus, Ayers ('84, p. 241, Plate 18, Figures 20-22; Plate 19, 

 Figure 5) has traced the development of the first and second maxillaj 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 ('84, 

 p. 596) says, "A rather striking variation was found in the first and 

 second maxillge of Blatta, which were formed respectively of two and 

 thi-ee 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'', 

 }). 19) states that in Forficula, " drei selbstandige Aeste zu erkennen 

 siud, 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 maxillfe. The cardo, stipes, galea, 

 lacinia, and palpus of Lepisma (Muhr, '77, Taf YIL Figur 45, or v. 

 Stummer-Traunfels, '91, Taf. IL Figur 11) not only agree in position 

 witli those of Blatta (:\ruhr, '77, Taf IL Figur 12, or Packard, '83\ 

 Plate XXVIIL 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, tlie first 

 maxillre of Collembola may be homologized with those of Orthoptera, 

 and hence all other Pterygote orders. I have traced the homoU)gies, 

 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 maxilla; arc but little specialized in form. 

 Heymons ('96, p. 19) states that in the Libellulid genus Epitheca, 

 " Erst spatcr gliedert sich von der Aussenseite der ^laxille cine kleine 

 rundliche Erhcbung ab, welche die Anlagc des Tasters darstellt (Figur 



