754 



Bashford Dean Memorial Volume 



Text-figure 61. 

 Attitude of a newly hatched Heterodontus japonicus, with its back arched upward, exploring the corners 



of the aquarium. 



From a drawing left by Bashford Dean. This drawing has been slightly modified to secure correct positions for the gill-clefts 



and the pectoral fin. 



ments of the grown fish, it swam easily and quickly, it readily changed direction, and I soon 

 found that it could swim around obstacles ; and, if touched, it could draw itself backward, using 

 its pectorals as supports. At first it was incUned to thrust its head out of water [Text-figure 

 60] as if anxious to escape,' and in doing this it showed considerable flexibility in its neck, and 

 it would even arch the back upward : at times it would explore the corners of the aquarium 

 [Text-figure 61], the head and anterior part of the body flexing downward: occasionally it 

 would bend the head, showing again the suppleness of the neck [Text-figure 62] . A period 

 of rest was next observed, then a period of activity, these alternating with more or less regu- 

 larity. A position of rest is shown [Text-figure 63] when the young fish raises its head, 

 spreads out its pectorals and depresses its unpaired fins, the tail flattened against the bottom, 

 the tip of the dorsals falling over on the (left) side. The latter habit may be explained in one 



of two ways: either as a survival of its flatten- 

 ing of the fins during the period of incubation, 

 or as a larval adaptation by which it becomes in- 

 conspicuous or less easily seized by a predatory 

 neighbor. The young fish impressed one with 

 the finished character of its movements: it 



Text-figure 62. 

 Diagram showing two attitudes of the 

 head of a newly hatched Heterodontus 

 japonicus, illustrating the flexibiHty of the 



neck. 

 From a drawing left by Bashford Dean. The gill- 

 clefts have been redrawn in a more nearly correct 

 position. 



