so. 2194. NORTH AMERICAN PARASITIC COPEPODS— WILSON. 15 



From these tables we may safely draw certain conclusions: 



1. In the majority of instances the torsion is inverse on the 

 right side and direct on the left side, but there is altogether too large 

 a minority in each case to warrant us in attaching any specific value 

 to the direction of torsion. 



2. On the fifth head the necks of the four parasites from the 

 center all entered the same opening in the skin of the host, and yet 

 one showed no torsion, two showed inverse torsion, and one showed 

 direct torsion. 



On the eighth head the first three parasites from the center all 

 entered the same opening in the fish's throat; one of them showed 

 no torsion, while the other two were strongly twisted in opposite 

 directions. 



On the ninth head the first three parasites all entered a single 

 opening in the right operculum of the fish, on the eleventh head the 

 first three similarly entered a single opening in the left operculum, 

 and on the fourteenth head the last three also came from one opening. 

 Hence we are forced to the conclusion that the position of the para- 

 site upon its host can not be the chief cause in determining cither 

 the direction or the amount of torsion. There must be some other 

 influence so much stronger than the position that it c;in completely 

 overcome the latter and produce its own effects in spite of opposition. 



3. With reference to the amount of torsion four or five successive 

 figures anywhere in the tables will show that for this species it pos- 

 sesses no significance whatever. 



But Quidor, in the article already referred to and in another later 

 one, went even further and argued that the genus Sphyrion, which has 

 been placed with the Chondracanthidae, and a new genus Ilepatophi- 

 luSj which he had just established, should be transferred to the Ler- 

 naeidae, because they both showed torsion. He stated that the males 

 of the two genera were unlmown, and that the females showed dis- 

 tinct torsion, "which is found only in the Lernaeidae" (p. XL). 

 There can be no question that they show torsion, but such a twisting 

 of the body is merely mechanical, and there is no reason why any 

 fixed parasite should not exhibit it, provided the anterior end of the 

 body is firmly anchored in the flesh of the host while the posterior 

 part hangs free in the water. On the contrary, there is every reason 

 why all such parasites should show torsion quite irrespective of their 

 morphology and ontogeny. But obviously we can not bunch them all 

 in one family on the basis of torsion alone, when there are good 

 morphological and developmental reasons why they should be 

 separated. 



Witli reference to the disposition of the above-mentioned genera 

 and others which have been crowded into the Lernaeidae, a full dis- 

 cussion will be found on page 34. 



