GENERAL BIOLOGY 



749 



cephali). We see from Fig. 533 that about 200 individuals of 

 this group were taken by us, belonging to some 20 species, 

 and I have represented in Chapter III. some of the most 

 peculiar new forms. Like most Atlantic fish-larvae these forms 

 are difficult to classify, because our knowledge of the different 

 developmental stages is deficient, and also because these larvae 

 pass through a remarkable metamorphosis before assuming the 

 ultimate shape of the adult. In a number of cases we are 

 therefore quite ignorant as to what larval forms develop into 



O < 100 Q 100 —250 p>250 Youngfish 



Fig. 544. — Distribution of Young Fish. 



the various known species belonging to the group of Apodes. 

 Our material is being examined by Einar Lea, and will prob- 

 ably help to clear up some of the difficulties mentioned above. 

 The stages belonging to Gastrostoinus bairdii (repeatedly 

 mentioned in Chapters III. and IX.; see Fig. '^:^, a, p. 97) 

 form a very interesting series, the stages a and b (see Fig. 545) 

 obviously being the transition stages between leptocephalus 

 and adult ; figure a plainly exhibits characters peculiar to the 

 leptocephalus as well as to the adult, and evidently forms a 

 more advanced stage of the transition. Another interesting 

 transition stage in leptocephali is exhibited by the form repre- 



