TENTH ANNUAL REPORT. 



121 



"#f / 



BUTTERFLY FISH, CHAETODON OCELLATUS. 



backbone, the fish being laid in a natural position. The slightly 

 heterocercal character of the tail is well defined. The connective- 

 tissue bones, usually injured in prepared skeletons, are shown in 

 their normal relations. 



The radiograph of the skate (Raia crinacea) displays the car- 

 tilaginous skeleton to good advantage for examination. The 

 attachment of the exterior spines to the pectoral rays and the 

 shoulder and pelvic girdles, with the claspers attached to the lat- 

 ter, are easily observed. 



The radiograph of the sea-horse (Hippocaiiipiis liiidsoiiiiis) is 

 a good presentation of the exoskeleton of fishes of its type, al- 

 though made from a dried specimen. Had a fresh specimen been 

 used the definition would have been sharper. This is the largest 

 example of this species ever brought to the Ac^uarium, and it is 

 shown natural size. 



In the Nautilus the radiograph shows the septa which divide 

 the air chambers and the connecting siphuncle. As an aid to 

 conchologists it would often be valuable, as, for instance, in re- 

 vealing the plates on the pillar in many of the Fusidcv. 



