424 



EPIZOA. 



to (fig. 219, b b) are, in fact, enormously developed ; they curve forward 

 after their origin from the posterior part of the trunk, and are so much 

 extended that they project considerably beyond the head of the creature, 

 where, becoming considerably attenuated, the two are joined together 

 by a kind of suture, and support, upon the point where they are united, 

 a cup-shaped organ whereby the creature fixes itself. This singular 

 instrument (represented upon an enlarged scale at fig. 220, l) is of a 

 cartilaginous hardness, resembles a little bowl the inside of which is 

 studded with sharp teeth, and is not only calculated to act as a powerful 

 sucker, but, from the hooks within its cavity, is capable of taking a 

 most tenacious hold upon the lining membrane of the mouth. 



(1090.) The other members (fig. 219, o) are much less developed, but 

 are nevertheless so constructed as to assist materially in fixing the 

 Epizoon ; they are represented upon a very large scale in fig. 220, 2, 

 where the outer pair (a a) are seen to exhibit, in the transverse lines 

 indented upon their surface, the first indication of articulated limbs, and 

 their extremities, armed with minute hooks, evidently form powerful 

 agents for prehension. Internal to these are two other jointed organs, 

 still more feeble in their construction, the ends of which (6 6), being 

 armed with three spines, will assist in efiecting the same object. 



(1091.) The mouth itself (fig. 220, 2, c) is formed upon similar prin- 



Fig. 220. 



Details of the structure of Achtheres. I. Adhesive disk on an enlarged scale : e e, conjoined ex- 

 tremities of the hinder pair of legs. 2. Structure of the mouth and parts adjacent: a a, anterior 

 limbs; b b, antennae ; c, mouth, furnished with rudimentary jaws. 



ciples, the external orifice being surrounded with a circle of minute re- 

 curved spines, well calculated to ensure its firm application to the surface 

 from which nourishment is obtained ; and within this, rudimentary jaws 

 furnished with strong teeth are visible, adapted, no doubt, to scarify the 

 part upon which the mouth is placed, in order to ensure an adequate 

 supply of food. In the male Achtheres, the sucking-bowl possessed by 

 the female does not exist, the prehensile organs being merely four stout 

 articulated extremities, armed at the end with strong prehensile hooks. 



