LERNEAD.E. 317 



thorax. This latter is generally of considerable size, whilst 

 the abdomen, in almost all the species, has become very 

 nearly rudimentary. Attached to the head, in the greater 

 number of the Lerneadae, we find one pair of antennae, 

 and two pairs of foot-jaws, by means of which they attach 

 themselves to their prey. In a few we find no antennae, 

 and only one pair of foot-jaws. We find no appearance 

 of eyes. The organs corresponding to the thoracic feet 

 of the Siphonostoina are variable in form, but in general 

 are almost rudimentary, sometimes, indeed, altogether 

 wanting. It is this very rudimentary state of the organs 

 of motion and other appendages that forms the principal 

 mark of distinction between the Lerneadae and the Sipho- 

 nostorna. The mouth, according to Kroyer, has generally 

 the shape of a blunt, spherical snout, placed on the most 

 advanced portion of the head, and terminating in a 

 roundish opening, though in some of the genera it is in 

 the form of a slight elevation merely, and is placed at 

 a considerable distance from the anterior part of the 

 head. 



The manner in which these animals fasten themselves 

 to the fishes upon which they live varies much. In some, 

 it is by means of the foot-jaws alone, which in these 

 species are strong, and of a hooked form. In others, it 

 is by means of two long appendages springing from the 

 upper part of the thorax, one on each side, and uniting 

 at the tip, forming at their junction a sort of round 

 button. In a third set, again, the organs of attachment 

 are a series of horns or appendages proceeding from the 

 side of the head. 



The females are generally furnished with large external 

 ovaries, containing numerous ova. The intestinal canal 

 is very distinct, extending through the whole body. It 

 is cylindrical, and widens towards the middle of its length 

 into a stomach. The motion in the living individuals 

 may be plainly seen, a series of rhythmical movements to 

 both sides, occurring to the number of from about sixty 

 to sixty -five in the minute ; besides a sort of peristaltic 



