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 epimerse, 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 2 - p 4 ), however, this sheath has been cast off, so as 

 to allow the spines and seta? to project freely. The branchial apparatus is not 

 yet iunctionally developed, the exopodal parts (br. 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 



