ORDER XII. LERNJSIDA 



890. The animals of this Order depart so widely from the 

 ordinary form of the Crustacea, that, until their early state was 

 known, they were ranked among the lower Articulata, and 

 placed next to the intestinal worms, as a distinct class under the 

 name of Epizoa. In their adult state, there is an almost com- 

 plete absence of members or appendages ; and those which re- 

 main are destitute of joints, being merely fleshy lobes serving to 

 attach the animal to the surface of that on which it lives. They 

 all bear a more or less close resemblance to the Lerncea, an animal 

 which is not unfrequently found on the eyes and gills of Fish. 

 The form of the adult is displayed in Fig. 611; 

 which shows its long suctorial trunk o^ pro- 

 boscis (a) ; its short thorax (b), bearing the 

 pair of legs (c), by which the animal is at- 

 tached ; its large abdomen (d), and its two 

 egg-capsules (e). The legs are united to 

 each other at their extremities ; and bear a 

 kind of sucker (/), which is applied to the 

 surface attacked by the animal, and assist in 

 retaining it there. The whole anterior part 

 of the body, however, is usually buried in the 

 substance of the part, from the juices of which 

 the Lernaea derives its nutriment. However 

 dissimilar the form and characters of this 



creature appear to those of even 



the preceding group, yet its con- 



nection with them is made evident in two ways. 



In the first place, there are numerous parasitic 



species, which depart less from the ordinary type ; 



forming a gradual transition from the Suctorial 



Crustacea of the last order, to the highly-aberrant 

 FIG. 612.-LARV* form presented by the Lernsea; so that, if the latter 



is excluded, it would be difficult to say where the 

 line is to be drawn. And again, the early forms of the Lernaea 

 (Fig. 612) so strongly resemble those of the Cyclops and other 



no. 611. LEBNJEA. 



