208 report — !878. 



within this cavity the small particles of opaque irregular granulose matter 

 move forwards and backwards with an uneven movement corresponding 

 to an irregular contraction of the walls of the alimentary canal. 



When this organism is so far advanced as to extend to the region beneath 

 the heart, it exists continuously to the terminal extremity of the pleon, 

 and the great dorsal artery, da, may be distinguished leading directly from 

 the heart to the terminal extremity of the animal, just beneath the dermal 

 surface of the embryo as it lies in close contact with the chorion of the 

 egg. The heart lies just beneath the dorsal posterior extremity of the 

 carapace, the posterior and lateral margin of which, mc, traverses the animal 

 just behind the heart in a slightly waved line to the eye. The antennae 

 have a distinctly appendicular appearance, and reach beyond the three 

 or four succeeding pairs of lobes, and terminate, one, b, in a single pointed 

 branch, the other, c, in two branches terminating in a serrated extremity. 



The oral appendages have not much departed from the lobular condi- 

 tion, but three other pairs, which appeared behind them, have enlarged 

 and are rapidly increasing and become double-branched. At the base of 

 these appendages the great opaline mass, ng, may be seen extending, being 

 apparently' doubled on itself, just behind the last pair exhibited, but in 

 reality following the inflection of the ventral surface of the folded embryo. 

 This continuous opaline mass may now readily be determined to be the 

 embryonic condition of the nervous ganglia. m 



The several parts from this time rapidly and regularly progress in the 

 development of their structure. The ophthalmic lobes gradually appear 

 to increase in condensation, every cell exhibiting a distinct but not very 

 opaque nucleus. The larger and rounder cells are nearer the periphery, 

 those that are deeper become compressed into angular shapes, while 

 those that are nearest the cornea arrange themselves in columnar 

 masses, most distinct towards their base. 



The antennae lie folded backwards along the margin of the carapace. 

 The mandible is directed inwards, and is invariably a single lobe, while 

 the two succeeding oral appendages are bilobed, with a tendency to 

 break up into more divisions. (PI. VII., fig. 7.) 



The development of the pleon is completed, as far as its external and 

 internal parts are apparent, at the period when the development of the 

 heart is advanced so that it is enabled to pulsate. The remainder of the 

 period necessary for incubation appears to be devoted to the completion of 

 the anterior appendages, and that of the internal viscera. (PI. VII., fig. 8). 



The vitellus is continuous with the development of the animal, and 

 exists in an inverse ratio with that of the growth of the embryo. When 

 it is entirely converted, the growing form has progressed as far as it is 

 capable through internal forces. To add to its further development, it is 

 necessary that it should obtain a fresh stimulus from agencies beyond its 

 own organization. Its vitality has advanced as far as it is capable, and 

 i f forces its way by the rupture of the egg-case into other conditions. 



As a free animal, the brephalus exists, as I have shown before, in 

 various forms, which are probably dependent upon the length of time 

 that the embryo remains in the ovum. For extended observation appears 

 to demonstrate that it quits the ovum of various genera in almost every 

 stage of its embryonic growth. 



