ANIMALS FOR. 67 



orifices through which the water passes, one carry- 

 ing to the animal inside the water holding food and 

 oxygen, the other allowing the water to escape. 

 The Ascidians are of various sizes and colours, and 

 most of them adapted for the Aqua vivarium. 



I would also draw the attention of the reader to 

 the beautiful Nudibranchiate Mollusca. They have 

 no shells, and are delicate creatures, the living 

 pearls, rubies, and garnets of the ocean. Those who 

 wish to know more about them should consult 

 Alder and Hancock's great work devoted to them. 

 This work was published by the Ray Society at a 

 cost of nearly three thousand pounds, and yet those 

 who know these elegant creatures best will say that 

 this money has not been uselessly spent in their 

 illustration. 



The Star-fishes, including the Sea- eggs and the 

 Sea-cucumbers (Echinodermcda), are another family 

 that claim attention. They are not very tenacious 

 of life, but are too interesting to be passed over in 

 our marine collections. The COMMON CROSS-FISH, 

 or FIVE-FINGERS ( Uraster rubens), is met with on 



FIG. 30, 



every coast. Their spines, their suckers, their 



beautiful cases, are all worthy of study, and they 



cannot be better studied than with Edward Forbes' s 



F 2 



