120 



NEW YORK ZOOLOGICAL SOCIETY. 



CHAMBERED NAUTILUS, NAUTILUS POMPILIUS 



ology of the parts which he closest to the plate showing the most 

 clearly. It will be noticed in radiographs of fishes that the skull 

 is not well defined, the numerous bones of the head making con- 

 fused impressions. It is probable that by splitting off half of the 

 head a clear impression could be secured. 



In salamanders the skull bones appear more distinctly, as well 

 as the position of the atlas bone. 



There are many characters, however, to be observed satisfac- 

 torily in the body aside from the skull, such as the relations of 

 the shoulder and pelvic bones to the vertebrse, and the relations 

 of the carpal and tarsal bones to each other, with their wide 

 separations by cartilages. The phalanges are easily counted. 



In the radiograph of Salaniandra and Diemyctylns a more 

 terrestrial habit seems to be indicated in the latter by the closer 

 articulation and greater development of the bones, especially those 

 of the limbs. 



The radiograph of the butterfly fish {Cliactodoii occllatiis) 

 brings out the osteology remarkably well. The demarcation be- 

 tween the dorsal and anal spines and the soft rays is clear, and the 

 interhaemal bones are distinct. 



That of the trout (Salz'eliniis fontinalis) shows a very straight 



