120 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
cause the paired mouth-parts are still at right angles to the germ band 
long after involution has occurred (Stage 5, Figures 5, 20). During 
this stage (7) the first maxille are attenuated toward their free ends ; 
a ventral view (Plate 5, Figure 29, mx.') shows their position in rela- 
tion to the lingua, and the extent of their convergence toward each other. 
The maxilla is quite unattached to the pharyngeal pocket (Plate 7, Fig- 
ures 44-50, cav. buc.) in which it lies, except where the margin of its 
basal aperture becomes confluent with the wall of the pocket (Figure 50) ; 
it has the form of a modified cone with an oblique, dorso-mesal, basal 
opening, as shown in transectious (Figures.44-50, mzx.1). The parts 
named stzpes and chitinous rod in my paper upon Orchesella are, as I 
have since found in that genus and in Anurida, distinguished simply by 
a greater deposition of chitin, and are connected above and below by 
delicate chitinized membranes, which I did not recognize until influ- 
enced by embryology to search for them. The “ chitinous rod,” then, is 
proved both by anatomy and development to be but a part of the 
stipes. 
During this stage (7) certain important differentiations of the first 
maxille are observable, if those organs are dissected out. The articula- 
tion between stipes and cardo (Plate 6, Figure 38, atc.) appears super- 
ficially as a notch, and in frontal section as a less chitinized region, 
as might be expected ; in a small hypodermal pocket is formed the stipal 
projection (Figure 38, pzj.) noticeable in the finished organ. The cardo, 
now transverse in position, was formerly the basal region of the lateral 
surface of the primary maxillary fundament, before the basal attachment 
became oblique. The articulation between the cardo and lingual stalk 
was described on page 112. 
In this stage, too, the head of the maxilla becomes vaguely separated 
from the stipes by a constriction (Plate 5, Figure 29). Later, the con- 
striction is more pronounced (Plate 4, Figure 25), and the apex of the 
head is fashioned inte an acute curving lobe, — the fundament of the 
galea (Plate 4, Figure 26, ga.) or “aussere Lade.”’ The “head ” is lined 
with a continuous layer of hypodermis cells. Next, on the mesal side 
of the head, a second lobe appears, the lacinia (/en.), or “ innere Lade.” 
Both galea and lacinia, then, become toothed on the mesal face, the 
teeth of the latter being produced each by a single cell ; the larger teeth 
of the former are secreted each by many cells. Eventually (Plate 6, 
Figure 39) the galea (ga.) becomes thickly chitinized except for a 
central hollow core, but the lacinia (/en.) remains thinly chitinized even 
in the adult. As in the mandibles, the hypodermis is finally excluded 
