FOLSOM: MOUTH-PARTS OF ANURIDA MARITIMA. 95 
Packard (’71, p. 18) says, regarding Isotoma, “‘ The clypeus, however, 
is merged with the epicranium, and the usual suture between them does 
not appear distinctly in after life, though its place is seen in Figure 13 to 
be indicated by a slight indentation. The labrum is distinctly defined 
by a well-marked suture, and forms a squarish knot-like protuberance, and 
in size is quite large compared to the clypeus. From this time begins 
the process of degradation, when the insect assumes its Thysanurous 
characters, which consist in an approach to the form of the Myriapodous 
head, the front, or clypeal region being reduced to a minimum, and the 
antenn and eyes brought in closer proximity to the mouth than in 
other insects.” 
Lemoine (’83, p. 510, Planche XV., Figure 24) mentions in Smynthu- 
rus, “ Les deux appendices qui constitueront la lévre supérieure,” but 
they appear in his figure as only simple lobes from a large, median 
labrum. 
Wheeler (’93, p. 57, Figure VI.) represents the labrum of Anurida as 
a median, unpaired fundament, and Claypole (’98, Plate XXIII.) gives 
several surface views of the upper lip in the same species. 
Uzel (98, Taf. VI., Figur 87) shows the single labral fundament of 
Macrotoma (Tomocerus). 
Regarding Campodea, Uzel (98, p. 26) says: “‘ Vor der Mundeinsen- 
kung erblickt man jetzt schon die unpaare Anlage der Oberlippe,” and 
partially illustrates (Taf. IV., VI.) the development, which proceeds 
essentially as in Anurida. 
The finished labra of Campodea (Grassi, ’86°, Tay. IV., Figura 7) and 
Japyx (Grassi, ’86°, Tay. II., Figura 15 62s) are very simple rounded 
plates. 
For Lepisma, Heymons (’97°, Taf. XXX.) figures the labral funda- 
ment as a prolongation from the procephalic lobes, and characterizes it 
(p. 591) as “eine kleine, vollkommen, ungetheilte, einfache Platte.” 
Later (p. 593) he says, “ Die Oberlippe wird bedeutend grésser und 
bekommt an ihrem hinteren Rande eine mediane Einkerbung (Figure 17).” 
The median indentation is clearly, however, a secondary formation. 
In both Lepisma and Machilis (Oudemans, ’88, Taf. I., Figur 3) the 
labrum remains simply an anteriorly rounded plate. 
In the Orthopteran CEicanthus, Ayers (’84, p. 240, Plate 18, Figures . 
21, 22) describes the unpaired fundament which forms the ovate labrum. 
In short, the labrum in all Orthopteran families develops from an un- 
paired fundament. (See Wheeler, ’93, Heymons, 795°.) 
The same is true of the Libellulide and Ephemeride (Heymons, ’96, 
