folsom: mouth-parts of anurida maritima. 107 



"The mandibles [of Calopteuus] remain single-lobed," and both Wheeler 

 ('93) and Heymons ('95'') represent them as simple papilljE in all fami- 

 lies of Orthoptera. It may at least be said, however, that the mandibles 

 of Collembola and Thysanura are certainly homologous in their entirety 

 with those of Orthoptera, and hence of all other insects. 



It is an interesting fact that Heymons ('96, Taf. II., Figur 29) dis- 

 tinctly i-epresents mandibular palpi for the larva of Ephemera, — a rare 

 condition ; indeed, Packard ('98, p. 61) terms this appendage of nymphal 

 Ephemerids a "lacinia-like " process, although Heymons states (p. 21) 

 that it is lateral in position, and so figures it. 



What embryological evidence there is, then, confirms the view based 

 upon anatomical data, that " the mandibles are primarily three-lobed 

 appendages like the maxilhe " (Packard, '98, p. 61). 



Turning now to the Myriopoda, the Symphyla, represented by the 

 single genus Scolopendrella, show marked affinities with Campodea, as 

 is well known. I wish here to emphasize especially the correspondences 

 between the mouth-parts of the two genera, which have never been 

 cai-efully compared in these respects. 



Latzel ('84, p. 8, Taf. L, Figur 5) describes the mandibles of Scolo- 

 pendrella as follows : "Die Oberkiefer bestehen jederseits aus einer fast 

 horizontal gelagerten, trapezoidalen Chitinplatte, welche am End- oder 

 Kaurande durch eine mittlere Einbuchtung in zwei Partien abgetheilt 

 erscheint, von denen die vordere in vier kraftige, die hintere in vier bis 

 fiinf kleinere Ziihnchen eingeschnitten ist. Eingelenkt sind diese Kie- 

 ferplatten mit dem hinteren und ausseren Eck in eine zwischen Kopf- 

 decke und Unterseite eingelagerte seitliche Lamina, welche einige 

 Aehnlichkeit hat rait der Wange der Insecteu und die von Menge als 

 Theil (Stamm) der Oberkiefer aufgefasst wird. Am inneren Hintereck 

 jeder der beiden Oberkieferplatten entspringt eine sehr kraftige Sehne, 

 die in eine betrachtliche Anzahl von Muskelbiindeln auslauft, welche sich 

 unten am Kopfrahmen inseriren." 



The mandibles of Scolopendrella therefore resemble those of Cam- 

 podea rather than those of anj- other insect, in that they are hollow, 

 with a basal (stipal) part articulated to the skull, and a head separated 

 transversely from the fulcrum. The head consists of two pi-imary lobes 

 (galea and lacinia) as in Campodea, but both are movable by muscles, 

 whereas in Campodea the lacinia alone is articulated, and even this no 

 longer has muscular attachments. The tendon and muscles which move 

 the lacinia of Scolopendrella are exactly similar in position and function 

 to the "chitinous rod " and muscles which adduct the head of the first 



