ECHINODERMATA. 



35 



bear calcareous spines. Within the tests are placed the fully- 

 developed alimentary canal, and the water-vascular and repro- 

 ductive organs. The starfish, &c., reproduce sexually. The 



^m 









S>w'- 





Pig. 8. — The Common Starfish (Uraster rubens). From Nicholson. 



ova produced give rise to curious larval forms, quite unlike the 

 adult. 



The group must be summarily dismissed here, as they are of no 

 importance to the agriculturist, except in the case of the starfish 

 (fig. 8), which are sometimes employed as manure, the so-called 

 "five-finger" manure, in neighbourhoods near the coast. 



