MORPHOLOGY OF TELEOSTEAN HEAD SKKLETON. 505 



II. Material and Methods. 



Part of the material requisite for my investigation was 

 obtained by keeping adult sticklebacks in small aquaria 

 during their breeding season ; the rest by hatching, under 

 the tap^ spawn found in a stream near London. In this 

 way it seemed possible to obtain a definite idea of the size 

 of the various embryos and larvae at different ages. During 

 the earlier stages this was possible ; but later oa, owing to 

 the groat variation in length of individuals l)olonging to 

 the same hatch, the attempt became useless. 



The following table contains a list of all the specimens 

 examined, with details which may prove useful to future 

 workers. 



Table of Specimens with Descriptions of the Stages. 



* Embryos that were fixed whilst in the egg. 



