656 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



Such a condition as the latter portra^'s, to be of an}' advantage to 

 the Argulus, would necessitate that the larva fasten itself to the fish 

 immediateh' upon emerging from the egg. In that case the expres- 

 sion " Jouit de toute sa liberte"' would hardly convey the correct mean- 

 ing. Van Beneden does not give this as his own personal observation, 

 and it will require considerable additional proof before it can be 

 received. The probability is strongly against it. 



When a suitable place has l)een chosen l)y the female the eggs are 

 deposited end to end in parallel rows, one egg at a time. The rows 

 are quite short and may contain anywhere from 3 or -i to 15 or 20 

 eggs, and there may be from 3 to or T rows together. The female 

 then rests for a while before depositing a similar lot in another place. 

 Often in an aquarium the entire lot of several hundred eggs will be 

 dei^osited close together on one side, but they are always broken up 

 into these smaller lots determined by the intervals of rest. 



As nearly as can be judged from a careful comparison of the state- 

 ments of various authors with original observations, there seems to be 



Fig. 2.— Eggs of Argui.v 



MEG A LOPS 



:'T READY TO HATCH. 

 0.28 MM. 



a tendency in A.yolktceus toward a fewer number of rows (two being 

 very common) and more eggs in each, while in ^1. catostomi the rows 

 are more numerous and shorter, giving to the individual batches of 

 eggs more of an elliptical outline (fig. 1). 



In A. 7negalops, on the contrary, all the eggs observed have been 

 laid in single rows, Avith from 6 or 8 to 20 or 25 eggs in each (fig. 2^ 

 Jurine (1806) has given us an admirable description of the process of 

 egg-laying in ^1. follaceKS, so accurate that it has not since been 

 altered in a single essential particular. T quote it in full. 



Toutes les fois que I'argule-mere a pondu un oeuf, elle fait mi petit pas qui avance 

 son corps en lui donnant un peu d'obliquite: de sorte que le second oeuf se trouve 

 n^cessairement place en avant et tl cote du premier. En alternant ainsi ses pas, le 

 troisieme oeuf se trouvera dans la direction du premier, le quatrieme dans celle du 

 second, et ainsi de suite; de maniere qu'ils seront disposes sur deux colonnes, dont 

 la premiere comprendra tons ceux dont les nombres sont impairs, et la seconde ceux 

 dont les nombres sont pairs. Telle est la marche que suivant ordinairement ces 

 femelles dans leur ponte; cependant il arrive quelquefois qu'elles deposent leurs 

 oeufs sur trois, quatre ou cinq colonnes, ou qu'elles les eparpillent ; mais ce denier 

 cas n'a lieu que lorsqu'elles sont inquietees. II arrive encore que les femelles entre- 

 coupent leur ponte et qu'elles la font en trois ou quatre reprises : alors elles changent 

 de place et se transportant ailleurs. 



