APPENDIX. 357 



gent: they are somewhat lance-shaped, and at 

 the extremity of each, on the under side, is a 

 mouth, with a sucker, divided by a fleshy trans- 

 verse septum ; by means of these suckers, the 

 mouths of this two-bodied monster are kept 

 steady, so as to suck without intermission. The 

 orifice of the mouth is large, and, when fully 

 open, triangular : there is also an organ within 

 the gullet which seems analogous to a tongue, 

 resembling the sucking organ of the pseudo- 

 leech. The alimentary canal branches out on 

 both sides into numerous blind vessels. The 

 whole of this canal, like the creature itself, is 

 cruciform. The circulation of the blood is very 

 visible : each half of the animal has on both 

 sides two principal blood vessels, which are 

 every where of almost equal diameter, without 

 any enlargement ; in the two exterior ones the 

 blood runs upwards, and in the two interior ones 

 downwards, and its motion is extremely rapid. 

 The generative organs and ovaries are also 

 double. The feces, as in the polypes and other 

 lower animals, pass out at the mouth. The two 

 lowest lobes are somewhat club-shaped, or thick- 

 est at the extremity, towards which, in each, are 

 two oval plates, or disks, containing four oblong 

 acetabula, or suckers : the bodies below the 

 plates terminate in a triangular piece, or flapper. 

 In some of their movements it seems as if the 

 two upper lobes had different ivills, since some- 



