Tank No. 17, 18, 19, 20. 



31 



Fig. 77. Dactyloptcrus voiitans (Flying-gurnard), 1/2 nat. size. p. 1 10. 



Tank No. 19. 



Cuttlefish {Sepia, p. 90, fig. 78). Like the Octopus and Squid 

 these are molluscs. Four to ten inches long and half as broad, 

 in shape like a small, big-headed, heavily-made fish. They 

 may be floating, but generally lie in corners on the sand 

 which they resemble in colour. The dirty colour of the water 

 is due to the ink they squirt out when disturbed. 



Fig. 78. Sepia officinalis (Cuttlefish), '/o nat. size. p. 90. 



Tank No. 20. 



Pelagic Animals (see Note on p. 57). These show best in bright 

 sunshine (from noon to two); many do not live long, and 

 the tank is richest after a calm dull day. The more delicate 

 are in wide glass cylinders, to prevent injury from the stream 

 of water. There may be present: 



Jelly fish. A. Medusae (p. 68). Carmarina (fig. 79), two or three 

 inches long, umbrella-shaped, perfectly transparent. Pelagia 

 (fig. 80), white with numerous spots. Olindias (fig. 81). Tima 

 (fig. 82). Rhizostonia (fig. 83), a white globe with a violet 

 border and a swelling violet and white stalk. Cotylorhiza 

 (fig. 84), from September to January; nearly a foot across. 



