THE SKATE-SUCKER. 



711 



lids 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 bath- 

 ing, I waded 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 HORSE-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 



HORSE-LEECH. Haemopls saagulsorba. 

 SKATE-SUCKER. Albtoae imuricata. 



earth-worm, 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 color, 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 com- 

 mon 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 larvae of the 

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



