104 
inside the lower part of the carapace. The latter is now distinctly defined not 
only inferiorly, but also posteriorly, and projects on each side in front to the 
rostral plates (R), which reach somewhat beyond the anterior extremity, though 
still far apart. In the interior of the body the liver (1) is now very distinct, 
being about to divide. Of the yolk-mass only a small, but sharply-defined 
rounded portion is left, enclosed in the developing stomach. Dorsally, the heart 
(h) is in process of development. 
Fig. 10 represents one of the last stages of the embryo, its size being 
almost twice that of the preceding stage. The Cumacean character of the 
animal is now very obvious, both as to its general form and the structure of 
the several appendages. The carapace is very large, and has assumed its 
characteristic shape, partly also exhibiting traces of the spiny armature of the 
dorsal face and the inferior edges. The rostral plates (R) are greatly prolonged, 
and are about to meet in front to form the pseudorostral projection. Their 
upper edges, however, are not yet in immediate contact with each other, nor do 
the plates exactly fit to the frontal part. At the end of the latter the ocular 
tubercle (0) is very distinct, the eyes being now confluent to a single median 
organ, tipped, as in the adult animal of this species (D. lucifera), with a pro- 
curved spine. Of the exposed segments of the trunk, the 4 anterior are nor¬ 
mally developed with distinct epimeral parts, whereas the last segment is very 
small, without any epimerae, and still having no traces of limbs. The tail is 
stretched out, so as now to extend more or less in the axis of the body, and 
its segments have assumed the peculiar nodular appearance characteristic of the 
adult animal, being defined by very deep instrictions. They are also somewhat- 
unequal in size, increasing in length to the penultimate one, which is the lar¬ 
gest. From both their dorsal and ventral faces scattered slender hairs have 
risen. Of the limbs, the mandibles and maxillae are now wholly admitted 
between the lateral parts of the carapace, whereas the succeeding limbs project 
more or less below. They are now all distinctly segmented, but in the superior 
antennae (a 1 ), as also in the 1st pair of legs (p 1 ), probably also in the maxilli- 
peds, the articulations are still enveloped by a thin membranous sheath. In the 
3 succeeding pairs of legs"_(p-—p 4 ), however, this sheath has been cast off, so as 
to allow the spines and setae to project freely. The branchial apparatus is not 
yet functionally developed, the exopodal parts (hr. exp.) being still discontinuous, 
whereas they will subsequently meet at the ends to form the ejecting tube pro¬ 
jecting from the pseudo-rostral prominence. The distal portions of these parts in 
the present stage are seen projecting downwards from about the oral region as 
thin linguiform lappets. The telson (t) is conically tapered, and tipped with 2 
