FORM AND LOCOMOTION 17 



not upside down. When taken from the water a Puffer will 

 generally inflate at once, but if slow to begin can be persuaded 

 to swell up by gentle tickling. In this condition, and with the 

 spines of the skin all standing erect, the fish is adequately 

 protected against most predatory enemies, who would find it 

 a difficult morsel to bite, much less to swallow. Recent obser- 

 vations made by Dr. Beebe, however, tend to show that such 



Fig. 



-FLATTENED FISHES. 



A. Female Thornback Ray (Raia davata), X yV \ B- Flounder {Flesus flesus), X^; 



c. Angel-fish {Pterophyllum scalare), X 5 ; d. Oar-fish or Ribbon-fish 



{Regalecus gles7ie),x about oV- 



protection is not always complete. He watched a number of 

 little Porcupine-fishes, and saw that when they were threatened 

 by a large Gar-fish, four feet in length, they bunched together 

 for protection, giving the appearance of one large, round and 

 prickly fish; occasionally, however, a single individual would 

 become detached from the mass, when it was promptly seized 

 and devoured. The allied Trunk-fishes {Ostraciontidae) are also 

 slow-swimming creatures, living at or near the bottom of the 



