THE SKATE-SUCKER 



711 



will not lay their cocoons in small tanks, but require large reservoirs lined with clay and 

 edged with weeds and other aquatic plants. 



I may perhaps mention that our British waters contain other species of blood-sucking 

 Leeches, which are found mostly in still or stagnant waters, and invariably gather to a 

 spot where the mud is thick, soft, and plentiful. Last summer, while bathing, I wade<? 

 through some mud in order to pick some very fine dewberries that were overhanging the 

 bank, and when I began to dress found that my feet were covered with Leeches of different 

 sizes. I counted eighteen on one foot, and then found that their numbers were so great 

 that I ceased to count them. 



IN the accompanying illustration we have two more examples of this curious family. 



The upper figure represents the common HOKSE-LEECH, which is so plentiful in our 

 ditches and more sluggish rivers. This annelid is distinguished from the preceding 

 by the character of its teeth, which are not nearly so numerous as in the medicinal leech, 

 and much more blunt. It is a carnivorous being, and feeds upon the common earth-worm, 



HORSE-LEECH. Hcemopis sangufcorba. 

 SKATE-SUCKER. Albione muricdta. 



seizing it as it protrudes itself from the banks 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 

 colour, which is greenish black ; whereas that of the medicinal leech is green, with some 

 longitudinal bands on the back, spotted with black at their edges and middle ; the under 

 surface yellowish green, edged, but not spotted with black. 



THE lower figure in the same 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. 



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

 means of moving their rings alternately, or they can proceed at a swifter pace by 

 employing a similar mode of progress to that which is made use of by the larvse of the 

 geometrical moths. Being furnished with a sucker at either end, they first fix their hinder 



