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the middle. That the male animal should be without 

 a mouth and digestive apparatus, we certainly were not 

 prepared to find, since the presence of the mandibles, 

 though unusually placed, induced us to expect the 

 existence of a prima via as much as we had deduced 

 its absence, from finding those organs wanting in the 

 female. 



The large lateral lobes of the cephalon are filled with 

 muscles, which hold and move the powerful mandibles 

 that can only exist as organs with which to grasp the 

 female. 



From the facts which have now been observed, assisted 

 by the elaborate labours of M. Hesse, we have arrived at 

 the following conclusions : 



1st. That Anceus of Risso and other authors, with 

 a large head and porrected mandibles, is the fully de- 

 veloped male state of this genus. 



2nd. That Praniza of Leach and other authors, with a 

 small head, is the female state, either in an unimpregnated 

 or gravid state, 



3rd. That the larva form of the animals of both sexes, 

 although closely resembling each other, may be distin- 

 guished at a very early stage of their growth, even if not 

 immediately after birth. 



We hope that the conclusions at which we have thus 

 arrived will be tested by close observers. There are also 

 some points of interest in the internal structure of these 

 animals that have yet to be worked out. 



