1919 Fasten; on Salmincola 163 



maxillae to the attachment tube, she remains thus attached until the com- 

 pletion of her life history. But it must be pointed out that prior to sexual 

 maturity, the second maxillae of the organism (Figs. 27 to 31, mx") in 

 both male and female are attached to the proximal foot of the attachment 

 tube (Figs. 28 to 31, t) ; whereas in the mature female these maxillae 

 (Figs. 34 and 35, mx") are in direct contact with the transformed chitinous 

 bulla (Figs. 3i and S5 bu) imbedded in the gill tissue. Now a question 

 which naturally arises is, how do the second maxillae of the adult females 

 come to occupy their final position? An investigator who did not secure 

 all of the intermediate stages between the time of the intitial attachment 

 of the first copepodid larva and the period when it reached sexual ma- 

 turity, might easily arrive at the same conclusion as Claus (1862), Vej- 

 dovsky (1877) and Wilson (1911 and 1915); namely, that soon after the 

 fusion of the second maxillae with the proximal end of the attachment 

 filament, the slender tube of the attachment filament shrinks and shrivels 

 up until the maxillae are brought into close contact with the distal bulla 

 enclosed in the flesh of the host. However, the results set forth in the 

 present paper do not confirm the observations of these investigators. As 

 already pointed out, shortly before reaching sexual maturity the female 

 grasps the gill with the chela-like maxillipeds, withdraws the claws of the 

 second maxillae from the foot of the attachment tube, and then by a 

 gradual creeping process along the attachment tube transfers these claws 

 to the posterior margin of the bulla, where they become permanently at- 

 tached. 



5. SUMMARY 



1. The first copepodid larva of Salmincola ed-wardsii (Olsson) Wilson 

 is a complex, highly developed organism, possessing two pairs of antennae, 

 a mouth tube, numerous paired mouth parts, and two pairs of swimming 

 feet. 



2. Internally the larva possesses an interesting attachment filament, 

 a tripartite eye, various glands, and fully developed muscular, digestive 

 and nervous systems. 



3. The digestive system in the first copepodid larva of Salmincola 

 cdxvardsii consists of a mouth tube with an upper and a lower lip, a 

 pharynx, an oesophagus, a stomach, an intestine and an anus. It is com- 

 pletely developed and capable of functioning. In this respect it is in 

 agreement with what Claus (1862) found for the digestive system of the 

 first copejiodid larva of Achthercs percariim Nordmann, but is not in 

 accord with what Wilson (1911) found in the larva of Achtheres amblopli- 

 tis Kellicott. 



