THE SKATE-8UCKER. 537 



It is a carnivorous being, and feeds upon the common earth-worm, seizing it as it protrudes 

 itself from the hanks of the stream in which the Horse-leech resides. There is a popular 

 prejudice against the Horse-leech, the wound which it makes being thought to be poisonous. 

 This, however, is clearly erroneous, and the creature has evidently been confounded with 

 another species, the Black Leech (Pseudobdella nigra). The Horse-leech is much larger 

 than the medicinal species, and may be known by its color, which is greenish-black, whereas 

 that of the medicinal leech is green, with some longitudinal bands on the back, spotted with 



SKATE SUCKER.— Aliione muricata. 



black at their edges and middle ; the under surface yellowish-green edged, but not spotted 

 with black. 



The figure in the accompanying illustration represents the Skate-sucker, so called 

 because it is found adhering to several fishes, and is especially prevalent on the common skate 

 and others of the ray tribe. Almost all the species of this genus are beset with the curious 

 nodules upon the rings of the body, which give to the creatures so strange an aspect. In this 

 genus, moreover, the portion containing the head is quite distinct and separated from the 

 body by a sort of neck. Our figure is of natural size. 



All these creatures have two modes of movement : they can crawl slowly along by means 



Vol. m.-6S. 



