148 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
cean hypopharynx, and possibly also to the median component of the 
Diplopod gnathochilarium. 
The first maxillze in Collembola and Thysanura develop essentially 
as in Orthoptera and may be homologized part for part with the maxille 
of generalized Pterygota. In Anurida a palpus appears in the embryo, 
but is resorbed before hatching, indicating the derivation of this genus 
from a form in which the first maxillary palpi were functional, as they 
are at present in Orchesella, Tomocerus, and other Collembolan genera. 
The first maxille of Campodea are clearly to be homologized with the 
first of Scolopendrella, the second of Chilopoda, and less clearly with the 
lateral portions of the Diplopod gnathochilarium. The first maxille of 
insects pass through a biramons condition, as in Crustacea, and the 
sclerites of these organs appear to be homologous in the two groups; 
the first maxilla of Hexapoda, however, are equivalent to the second 
maxillte of Malacostraca. 
The labium in Anurida develops from a pair of papillee, from which 
the entire gular region is derived. A palpus appears, but is soon re- 
sorbed, and no galeal and lacinial lobes are differentiated. Upon the 
whole, the labium among Apterygota is homologous with the same 
structure of Pterygota, although fewer sclerites are formed in the 
former group. The labium in insects, homodynamous with the man- 
dibles and first maxilla, agrees in detail with the first maxillipedes of 
decapod Crustacea. The labium of Campodea is homologous with the 
“second maxille” of Scolopendrella and the maxillipeds of Chilopoda, 
and is represented in the gnathochilarinm of Diplopoda. 
The sides of the face in Anurida develop from two lateral evaginations 
of the germ band near the mandibular segment, which eventually involve 
the labral and labial fundaments and complete the buccal cone. The 
mouth-folds of Collembola, Campodea, and Japyx are strictly homologous 
with the gene of Pterygota. The dorsal region of the skull in Anurida 
does not differentiate into sclerites which may be compared with those 
of Pterygote insects. 
The tentorium is inferred to develop from cells which have been pro- 
liferated from the ectoderm. 
The evidence convinces me that there are just seven somites in the 
head of Anurida, and that probably the same is true for all Hexapoda. 
The cephalic somites are successively: ocular, antennal, intercalary, 
mandibular, superlingual, maxillary, and iabial. As I have found — 
embryonic ganglia for the intercalary and superlingual segments, there 
are seven cephalic ganglia, one for each somite. Moreover, excepting 
