THE CHONDROCRANIUM IN THE ICHTHYOPSIDA. 89 



should have only family rank in that order. Summariz- 

 ing his conclusions, he maintained that the Cfficilians were 

 descended from Amphiuma-iike forms and these in turn 

 were oflfshoots from some amblystomoid Urodele. The 

 cousins Sarasin, while agreeing with Professor Cope in 

 the view that the Cfficilians and Amphinma were nearly 

 related, regarded the relationship as differing in this re- 

 spect. Amphiuma was a neotenic Crecilian, a larval Cae- 

 cilian become sexually mature. My problem was to 

 ascertain in how far the chondrocranial structures gave 

 support to any of these views. 



(2) The fact that the Dipnoi possess lungs led to 

 the view, which has obtained wide acceptance, that these 

 ancient fish-like forms were the ancestors of the Batra- 

 chia, and this view has received no little support from 

 Huxley's short but most suggestive discussion of the sus- 

 pensorial apparatus in the Ichthyopsida. More recently 

 several students have maintained that the Batrachia have 

 sprung from the Crossopterygian Ganoids and that the 

 only relationship that can be traced between Dipnoi and 

 Amphibians is that the lung-fishes may have had the same 

 ancestr}'', but that they can in no wise be considered as in 

 the line of batrachian descent. In how far does the chon- 

 drocranium support either of these views? 



It has not been my purpose to enter the broader field of 

 the relationships of these different groups as is shown by 

 other features. I have confined myself closely to the 

 chondrocranium and my results are to be regarded as 

 merely one factor in deciding these questions ; a factor in 

 itself of minor importance. 



I take as the basis of my studies the development of 

 the chondrocranium of Ambhj stoma punctata^ since of this 

 form I have had the most abundant material. This is 

 followed by an account of certain stages of the chondro- 



KS8EX INST. BULLETIN, VOL. XXVIII 6* 



