74 Invcrtebrata. 



earthworm about its middle, the hinder segment dies 

 after a short time ; the fore segment will probably live 

 and its wound heal. Similarly, if we cut the anterior 

 four or five segments away the small fore fragment 

 will soon die, while the large hind mass will recover. 



CHAPTER XIV. 



MOSS POLYPS AND TUNICARIES. 



CLASS IX. Moss Polyps (Bryozoa). The broad 

 leathery fronds of the tangles along our shores are 

 often encrusted with beautiful lace-like patches of 

 regular and minute patterns. If we put a fresh, 

 living piece of this into a vessel of sea- water, we 

 find that each of the cell-like spots is the home 

 of an elegant little organism which may be seen to 

 protrude through the mouth of its cell a delicate little 

 crown of tentacles. Each colony of these animals con- 

 sists of a common stock, bearing numerous little cham- 

 bers, each of which contains its delicately organised 

 inhabitant. Some of the little creatures become 

 modified into bird's-beak-like graspers with two horny 

 jaws, for the protection of the colony (fig. 45, B) ; 

 others become altered into globular pouches for the 

 reception of the eggs after their extrusion. Each of 

 the dwellers in these little cells consists of a saccular 

 body containing a looped digestive canal, in the bend 

 of which a nerve ganglion is placed, and it is provided 

 with a crown of hollow tentacles guarding the mouth. 

 Most of these moss-polyps are marine and have 



