416 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxn. 



same form as in the adult, with the exception that the endopod of the 

 first pair is three jointed instead of two jointed. 



Abdomen large and regularly elliptical, being a little longer than 

 wide; anal sinus deep and triangular, the lobes on either side evenl}^ 

 rounded; anal papillae large and basal, each armed with four long 

 curved set* which reach well beyond the posterior margin of the 

 abdomen. We do not find in this abdomen the few large skin glands 

 on either side which were so prominent in the megalops larvae, but 

 instead a large numlier of tiny glands scattered over the entire dorsal 

 surface, with a row of six or seven on either side of the intestine a 

 trifle larger than the rest. 



Total length, 0.66 to 0.7 mm. Length of carapace, 0.43 mm. 

 Width of carapace, 0.4T mm. Length of free thorax, 0.147 mm. 

 Length of abdomen, 0.125 mm. 



The larva of ^1. funduli thus takes its place with those of A. mega- 

 lops and A. dizostethii as one in which most of the metamorphosis 

 takes place within the Qgg before hatching. 



Like the two species mentioned the larva, when it does come forth, 

 has the same appendages and structure as the adult, with the single 

 exception of the first maxillipeds. Even these, however, are pre- 

 hensile, although by means of a claw instead of a sucking disk. As 

 soon as they come out of the &gg these larvse begin to swim by means 

 of the same appendages which they are to use through life. In the 

 case of megalops and stizosteth'd this is what would naturall}^ be 

 expected, the former spending sixt}^ and the latter eighty days in the 



egg- 

 But these y)Y??,(;/wZ/ larvae hatched in eighteen days, and it is at least 

 noteworthy that they were able to reach the same advanced develop- 

 ment in so small a fraction of time. 



The digestive tract and the circulatory apparatus are not as far 

 advanced in the present species as in megalops^ and presumably in 

 stizostethii., although we have no record in this respect for the latter 

 species. But in external morphology, and particularly in the loco- 

 motor apparatus, these eighteen-day larvae have fully reached the same 

 advancement a>^ the other two species. 



III. THE LARVA OF ARGULUS MACULOSUS Wilson. 

 Plate XXXI, figs. 15-22. 



Two females of this species with ripe eggs were obtained at Lake 

 Maxinkuckee, Indiana, August 8, 1906, from the redeye, Amhlopl/tes 

 nipestrls. It was afterwards found that this was not their true host, 

 but only a temporary one, used while they were searching for a suit- 

 able place to deposit their eggs. 



Numerous specimens of both sexes were subsequently obtained from 

 the two catfish, Ameiurus natal is and ^1. nehulosus^ which are evidently 



