438 University of Kansas Geological Survey. 



from its mouth. These tentacles possess cells in which jagged, 

 thread-like processes lie coiled up in a narcotic fluid. Objects 

 coming in contact with the tentacle cause the cells to burst and 

 throw the thread like a lasso around the object, which, if it be 

 animate, is poisoned by the fluid. Other marine hydra pro- 

 duce polyps on flinty tubes, from which they project like flowers 

 from the parent, and form a bell-like body with many long, 

 radiating tentacles. In this form the hydra is called a jelly- 

 fish. These jelly-fish produce eggs which in turn produce 

 polyps. The contractile tissues, which are muscle-like in struc- 

 ture, propel the animal through the water. 



Echinodermata. 



Echinoderms have a well-developed skeleton which is com- 

 posed of calcareous plates, or of calcareous bodies imbedded in 

 the integument. The subkingdom is represented by rayed 

 animals such as the star-fish, in which the rays spring from a 

 common center ; by the sea-lilies, in which they start from a 

 fixed stalk ; by the sea-cucumber, which is covered by spicules 

 of calcareous matter; by the sea-urchin, in which the rays are 

 coiled, forming a globular body. The Echinoderms have a 

 digestive tract separate from the body cavity. The sea-water is 

 driven into this cavity, or gastro-vascular space, through canals 

 by cilia. Some of the members of this subkingdom have rudi- 

 mentary eyes. The star fish has an eye composed of many 

 crystalline lenses at the end of each ray. The test of an Echin- 

 oderm is composed of calcareous plates which are arranged 

 in concentric rows. The principal classes of Echinodermata 

 are : Cystidea, Blastoidea, Crinoidea, Asteroidea, Echinoidea, 



and Holothuroidea. 



Vermes. 



The representatives of this subkingdom possess a segmented 

 structure. The segmented body of these animals contain a 

 nervous system which consists of a double chain of ganglia 

 passing along the ventral side of the body. Some species are 

 provided with locomotive appendages, while some of the mem- 



