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 iiagella. They are, 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 theni 

 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 2 ) 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 instructions 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 anrmlated. In the 

 1st of these pairs (the 1st pair of maxillipeds mp 1 ), the exopodite (br. exp.) has 

 assumed the form of a thin lamella projecting downwards in front of the endo- 

 poclite, 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 



