88 MULLER ON THE MALE OF 



the structure of their place of attachment, they are intended to 

 be detached *. In all probability, finally, the thin appendage 

 of the Hectocotylus in Argonanta and Tremoctopus finds its 

 way into the female sexual aperture only after the separation, 

 for we find almost all Hectocotyli filled with semen, and the 

 penis of Hectocotylus Tremoctopodis often is in an apparently 

 virgin condition. This is easily possible, considering the lively 

 twisting movements which the appendage in both Hectocotyli 

 makes, even independently of the rest of the body, and in Hec- 

 tocotylus Tremoctopodis it is rendered still more easy by the cir- 

 cumstance that in the other portions of the penis the epithelium 

 forms a multitude of recurved hooks, the hinder edge of each 

 cell riding on its neighbour. It is to be considered, however, 

 whether preliminary acts of coition do not first determine the 

 separation of the Hectocotylus from the rest of the animal. 



It is remarkable enough, anatomically, that certain Cephalopod 

 males should be distinguished from those of the immediately 

 allied species by the presence of the Hectocotylus-arm ; but the 

 facts adverted to render the relations of the detached Hectoco- 

 tylus so peculiar, that one is forced either to remain in doubt, or 

 to come to the conclusion that the line of demarcation between 

 independent animated beings, and such as are not so, is by no 

 means so distinct as the schools draw it. 



It is, however, hardly the time at present to draw any theo- 

 retical conclusions, when so many matters of fact remain to be 

 inquired into with regard to the known species of Hectocotylus 

 (and there may be others), by which perhaps all that has been 

 done may be upset again ; for what has been stated here can 

 only indicate in what direction future investigations must be 

 undertaken. I thus sum up the chief results : 



1. Perfect male Argonauts occur distinguished from the fe- 

 males, which only have hitherto been known, by the absence of 

 the expanded " vela " upon the two upper arms. 



2. These male Argonauts carry the Hectocotylus Aryonautce 



* It is important to know whether changes in the size and form of all Hec-> 

 tocotyli occur after their separation ; whether, for example, the coalescence of 

 the everted edges of the skin in Hectocotylus Argonauts happens before or 

 after separation from the rest of the animal. In my free specimens the pig- 

 mented capsule was in all cases fully formed. 



