102 
the embryo a slight arched ridge (C), indicating the lower edges of the developing 
carapace, and above this ridge, imbedded in the yolk-mass, appears a sharply 
defined circular area (1), representing the first indication of the liver. 
Figs. 6 and 7 represent a much later stage, in which, however, the dorsal 
curvature is still well marked. The larval skin has now been cast off, whereby 
all the appendages appear freely projecting. The caudal part of the body is 
still very 'short, as compared with the anterior division, and is abruptly curved 
upon the latter. It is distinctly segmented, whereas the segmentation of the 
adjoining part of the trunk is still imperfect. At the broadly rounded anterior 
extremity, just above the insertion of the superior antennae, 2 small pigmentary 
masses (0), well defined from each other, are seen, representing the first intimation 
of the visual organ, which in this stage is double accordingly (see fig. 7). The 
superior antennae (a 1 ) have considerably increased in size, and now exhibit a 
distinct boundary between the peduncle and the 2 flagella. They tire, however, 
still extended behind along the sides of the embryo. The inferior antennae (a 2 ) 
and mandibles (M) have retained their appearance almost unaltered. Below them 
in the middle, the oral aperture has appeared, being limited in front by the 
very prominent anterior lip (L), and behind by the 2 lappets of the posterior 
lip (1). The maxillae (m 1 , m s ) are more deflexed, otherwise not very different 
from those in the preceding stage. The 7 succeeding pairs of limbs, on the other 
hand, have considerably increased in size, the endopodites having now assumed 
a digitiform appearance, with slight instrictions indicating the incipient segmen¬ 
tation. In all these pairs, however, they are still curved backwards, as in the 
preceding stage. The exopodites in the 3 middle pairs have likewise increased 
in size, though they are scarcely more than half as long as the endopodites. Like 
the latter, they are, curved backwards, and already exhibit a distinct boundary 
between the basal and terminal parts, the latter being closely afmulated. In the 
1st of these pairs (the 1st pair of maxillipeds mp 1 ), the exopodite (hr. exp.) has 
assumed the form of a thin lamella projecting downwards in front of the endo- 
podite, and terminates in a narrow linguiform lappet. In the 2 posterior pairs, 
the exopodite has retained its knob-like character, and in the 2nd pair (2nd pair 
of maxillipeds) scarcely any trace of it is left. The uropoda (urp) now exhibit 
a distinctly defined, but still rather short stem and 2 lanceolate rami. They 
are curved downwards, embracing the hind part of the anterior division. Beyond 
them, the extremity of the tail projects as an obtuse prominence, the developing 
telson (t). The lower part of the carapace (C), only faintly indicated in the 
preceding stage, now appears with great distinctness, and projects in front on 
each side to a lanceolate lappet extending to the oral region. These lappets 
