EEPORT ON THE SCHIZOPODA. 157 



As regards the limbs, the anteunulpe, the antenute, the mandibles, the two pairs of 

 maxillae, and the maxillipeds are nearly of the same appearance as iu the preceding 

 stage. Now, however, the first trace of two additional pairs of limbs have made their 

 appearance, the one occurring immediately behind the maxillipeds and representing the 

 first pair of legs, the other placed on the first caudal segment and representing the 

 first pair of pleopoda. Meanwhile, both have still the character of simple, non- 

 articulate, conical processes, without exhibiting the slightest trace of bristles or any 

 other form of armature. Moreover, the uropoda have increased somewhat in size, and 

 the terminal plates have become distinctly defined from the basal part, and furnished at 

 the tip with a few slender setae. The length of the larva in this stage is 2'65 mm. 



Intermediate Furcilia Stage (fig. 6).— In this stage the carapace has lost its 

 posterior spiniform projection, and the frontal plate has become narrower and more 

 pointed. The two additional limljs mentioned above, and forming, in the preceding 

 stage, merely simple non-articulate processes, have become more fully developed, being 

 distinctly articulate and provided with a few setae, and the first pair of pleopoda are 

 even, in living specimens, found to act as swimming organs. In addition, several 

 other budding limbs may be observed, viz., immediately posterior to the newly formed 

 first pair of legs, the first trace of the following (second) pair of legs, and on each of 

 the four medial caudal segments a pair of small conical processes, representing the 

 corresponding pleopoda. Moreover, three of the luminous globules have made their 

 appearance, viz., the foremost pair on the trunk, lying within the coxal joints of the first 

 pair of legs, and the most anterior of the odd globules belonging to the tail. The 

 telson and uropoda, finally, have slightly altered in form, the former being now^ some- 

 what narrower, and the latter a trifle more produced. Length of the larva 3 '20 mm. 



Last Furcilia Stage (fig. 7). — In this stage all the pleopoda have become developed, 

 and act in the living animal as true swimming organs. On the trunk the second pair 

 of legs have become articulated, though they are stiU much smaller than the first, and 

 behind' it a few minute bud-like pi-ojections may be seen, apparently representing two 

 additional pairs of legs, besides the first trace of the gills. The antennas until now 

 have retained their original form and function unaltered, acting as powerful natatory 

 organs, but in some specimens belonging to this stage the long plumose setae are found 

 to be partly obliterated, thus proving their original function as swimming organs to be 

 nearly finished. The frontal plate of the carapace has lost 'its marginal dentition, and 

 is very narrow, assuming accordingly a form more in relation with that of the adult 

 animal. Length of the body 3 "60 mm. 



First Cijrtopia Stage (fig. 8). — The character distinguishing most prominently this 

 stage from those preceding it, is the total change in structure and function of the 

 antennae. These limbs now cease entirely to act as swimming organs, and hence have 

 lost their great mobility, being now invariably extended forwards, and not, as in the 



