NO. 1368. 



DESCRIPTIONS OF AEG VLIDJ'J— WILSON. 



fi85 



the center. Each of the five anterior ones gives off a single pair of 

 nerves, while the sixth and last one gives off two pairs. The nerves 

 from the first ganglion, which is consideral)ly the hii'gest of the six, 

 go to the sucking disks; a ])ranch arises from this nerve very soon 

 after it leaves the ganglion and passes forward to the moutli ])arts. 

 The nerves from the second ganglion are a little larger than any of 

 the others, which is fully accounted for when it is found that they 

 ijuickly divide, one large branch going to the second maxillipeds and 

 the other innervating the lateral areas of the carapace. 



The nerves from the third, fourth, and lifth ganglia and the hrst 

 pair from the sixth ganglion supply the swimming legs in order on 

 either side. The last pair of nerves which are given off from the pos- 

 terior border of the sixth ganglion innervate the reproductive organs. 



Reproductive organs (fig. 10). — These are beautifully typical and can 



Fig. 11.— Semen receptacles and papill.e of argulus americanus female under greater 

 enlargement. 6. i., basal lobes of posterior legs; s. rf., dvcts leading from the recep- 

 tacles to the papill.e; s. p. semen papilla; .«. r., semen receptacles: t. )).. tactile papill.e. 



be plainly seen through the outer covering, even in preserved and 

 mounted specimens. In the female the semen receptacles {s. /., fig. 11) 

 are large and close together; the semen papilhv (s.p.) are also large and 

 the hardened chitinous tip of the duct which leads to them fi'om the 

 receptacles projects forward rather than inward toward its fellow on 

 the other side. In the figure the tactile papilhv (f.p.) used for ovi- 

 positing are much smaller than the average, and the specimen was 

 selected for this reason, since these papilhe would conceal the under- 

 lying organs as little as possible. 



The r(>lative size shown in the full-length figure of the femaliHtig. -2) 

 is nearer the average. 



In the male the essential organs (fig. 12) are ([uite typical. I)ut the 

 accessor}" organs surpass those of any species so far examined. In 



