672 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



It is to be regretted that the megahrps larvae could not be carried 

 beyond the initial stage, but they had t > be kept in salt water, and the 

 supply of salt-water fish and other life was necessarily limited so far 

 inland. Although tried with sev^eral possible hosts, nothing could ))e 

 found that was acceptable, and after living for ten da3^s without any 

 change they finally perished. We have also no record of the ^iizo- 

 steth'd larvje beyond the first stage, and both must r)e left for future 

 research. 



^\\'^ foJ hiceus and catostomi larva? agree closely in their development; 

 the first molt takes place about the fifth day and produces a radical 



change in the appendages 

 (fig. 10). The long rowing 

 branch of the second anten- 

 na^ and the temporary man- 

 dibular palps disappear, the 

 former being replaccnl by a 

 structure similar to that in 

 the adult, the latter never ap- 

 ])earing again. 



The disappearance of these 

 temporary larval organs of 

 locomotion of course means 

 that th(^ permanent swinmiing 

 legs have now become sulfi- 

 ciently developed to perform 

 their normal function. 



Though not yet like those 

 of the adult in all details^ 

 these legs have the same num- 

 ber of joints and approxi- 

 mately the same structure. 

 Fig. 10.— Larva of argulus foliaceis after the first There lias been a correspond- 



MOULT (from CLAUS). a. HI.. ANTERIOR MAXILLIPEDS • -J " £ +K +1 .„ ,, 



JUST BEGINNING TO CHANGE INTO SUCKING DISKS; ^.. '^^^ WldcnlUg of thc thoraX 



SKIN glands; k., heart; J., STOMACH BRANCHES; .s.f/.. aud abdouicn; tlic postcrlor 



LUMEN. '"''"'"^ '■' ''^"'' '"''"''''' ''°'' ■' '''"'''"' border of the latter has be- 

 come emarginate, and the 

 very nmch reduced papilh« are no longer terminal on each lobe, l)ut 

 lie close together in the center of the sinus just above the anus. 



The seminal receptacles and testes have enlarged considerably an.l 

 the former has accjuired a thin cellular covering. 



The unpaired ovary now appears as a row of small cells along one 

 side or the other of the intestine posterior to the stomach. These 

 cells increase in size, proliferate to the right and left and backward 

 and forward, and their granular contents gradually change with fur- 

 ther development. 



