386 GEOLOGICAL SURVEY OF THE TERRITORIES. 
Taf. I, Fig. 6, md), retain the palpus, which is represented by a single se- 
tose bristle, the remnants of the large part of the Nauplian third leg. The 
teeth on the cutting edge in Branchipus stagnalis are finer and more nu- © 
merous than in the. two other families. 
The first maxille.—Succeeding the mandibles are two pairs i maxille 
in the Limnadiade and Branchipodide, whileinthe Apodide there appears 
to be but a single pair of maxillz, which are succeeded by a rudimen- 
tary gill-bearing appendage, the maxillipede. The first pair of maxille 
in Limnadia gigas are described and figured by Lilljeborg; those of 
Estheria mexicana by Claus. According to Lilljeborg the first maxilla 
of Limnadia consists of but a single lobe with very numerous uniformly 
dense, fine, slender, and very long setose sete. 
In the Apodide the first maxillve consist of two parts, the basal (Plate 
XXI, figs. 9, 10), which consists of a single large chitinous piece, with 
the free cutting edge provided with two kinds of teeth, an inner sub- 
inarginal row of stout, acutely triangular teeth, while there is a@ mar- 
ginal row of hair-like sete. In Lepidurus the external portion of the 
cutting edge is somewhat differentiated, there being here, as seen in 
Plate XXI, fig. 9, a specialized portion with three stout teeth; this 
becomes obliterated in Apus lucasanus, but in the larva of the same 
species, as Dr. Gissler’s drawing (Plate XX XV, fig. 5) shows, this por- 
tion is at first separate trom the rest of the cutting edge, and in Lepe- 
durus this feature is retained in adult life. ‘Situated close behind the 
large chitinous portion and loosely connected with it at base is what I 
should regard as the palpus (Plate X XI, figs. 7, 8,13); that this should 
be regarded as a portion of the first maxilla is, I think, proved by ref- 
erence to the condition of the maxilla in the larva. By reference to Dr. 
Gissler’s figure of the maxilla of the larval Apus lucasanus this palpus- 
like portion is clearly seen to be a large flat bilobed portion lying behind 
but next to the outer part of the cutting edge of the maxilla. 
The maxilla proper, 7. e., the cutting or main portion of the appendage, 
is with good reason homologized by Lankester with the first endite or 
coxal lobe (his gnathobase) of the feet of Apus. The piece which we 
regard as the palpus, Lankester is apparently disposed to regard as a 
part of the maxilla, and not, as Zaddach thought, the second “maxilla. 
In the Branchipodide the first maxillze have ‘been best described and 
figured by Spangenberg (Taf. I, fig. 5). It consists of a broad, flat 
maxilla, the inner edge, 4. e., that corresponding to the cutting toothed 
edge of the maxilla of Apus, but which is smooth, with fine, delicate, 
hair-like sete; while appended to it on the hinder side is a large palpus 
with long, slender, stiff sete. The same partsare represented by Dr. Giss- 
ler in the first maxilla of the larval Streptocephalus texanus (Plate XX XIV, 
fig. 6), where the maxilla without sete and its stout palpus with two 
sets of setz are represented. When the larva is 5 millimetres in length 
a considerable change has taken place in the palpus; one of the outer set 
of bristles has become barbed; while the inner set, originally vanes d 
of three setose bristles, is now composed of eleven setae. 
The second maxille.—in Limnadia gigas, according to Lilljeborg, the 
second pair of maxilla are very much smaller than the first pair, and are 
rounded on the free edge, which is provided with long setiferous bristles 
and short stout ones. 
In the advanced larva of Estheria according to Claus’s ‘ Untersuchun- 
gen,” ete, Taf. xix, fig. 1, the second mavxillzare very small, slender, two- 
jointed appendages, ‘consisting of two portions, apparently the maxilla 
proper and an outer, slender palpus. 
