3412 



THE WORM-LIKE ANIMALS 



capable of the effort; but the muscular system of these animals is in reality highly 

 developed, as is shown by the strenuous resistance offered to any attempt to drag 

 them from their burrows. 



In Britain there appear to be about twenty kinds belonging to three genera, of 

 which the richest in species are Allolobophora and Lumbricus, Allurus including 

 only the square-tailed worm. Earthworms appear to be spread over all the tropical 

 and temperate parts of the world, and in some countries attain a size far surpassing 

 that of the English species; one of the largest (Microchceta rappi] being an inhabit- 

 ant of South Africa. The average length of this creature is four or five feet, 

 although it is capable of stretching itself much further, and its width is about 

 equal to that of a man's finger. On account of their burrowing habits, worms are 

 not very frequently seen, although periodically but only after heavy rains 

 they come to the surface of the soil in some numbers. Allied to the earthworms 

 is the rare and extremely slender Phreorydes menkeanus, which lives from 

 preference in wells and shallow water, in which it may be found in the greatest 

 abundance in May and June, disappearing in the winter. Another aquatic 

 member of the group is Tubifex rivulorum, a small red, translucent little worm, 

 found abundantly on the slimy bottoms of ditches and brooks. These creatures 

 remain with the fore part of the body stuck in the slime, while the hinder end 

 keeps up a continual vibrating movement. Usually they are so closely packed 

 that the surface of the mud appears to be red colored, and when startled, the 

 whole throng disappears like a flash into the slime. The clear transparent naids 

 behave in quite a different manner. These animals are also found in ponds 



and ditches, where they 

 may be seen winding 

 themselves in and out 

 among the stems of 

 duckweed. One of the 

 best known is the beaked 

 nais (Nais proboscidea ) , 

 so called from a feeler- 

 like prolongation of the 

 head, which is furnished 

 with two conspicuous 

 eyes. These worms 

 frequently reproduce 

 spontaneously by fission, 

 and it is not uncommon 

 to see one individual in 

 process of giving rise 

 to several others. 

 Among the bristle 

 worms is placed the 

 family Myzostomatidce, 

 BEAKED NAIS, Nais proboscidea (enlarged ten times). which was long a puzzle 



