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ANNALS NEW YORK ACADEMY OF SCIENCES 



Figure 3 



1. Outline restoration of Coccostens, a primitive arthrodire. After Patten. 



The well-armored head and thorax are sharply differentiated from each other. They 

 are connected by a peg-and-socket joint in the neck region. 



2. Outline restoration of an antiarch, Bothriolepis. After Patten. 



Head and thorax are well defined, but the head is less movable than In Coccosteua- 

 Very probably the oral and the branchial pouches with their respective muscles were 

 becoming differentiated from each other. 



3. Longitudinal section of Bothriolepis, showing the lack of endoskeletal structures, 

 such as calcified visceral arches and the dermal character of the functional jaws. After 

 Patten. 



4. Outline of Pteriehthys. After Patten. 



