14 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I42 



Among the Beryciformes the two apparently extreme types of 

 caudal skeleton have been well illustrated. In Polymixia (Regan, 

 1911a, fig. i) the first preterminal vertebra has a normal spine but 

 no neural crest, the anterior uroneural is wedged into the terminal 

 vertebra, and there is one postterminal centrum. In Hoplopteryx 

 (Regan, 1911a, fig. 2) the first preterminal vertebra has a crest but no 

 neural spine, the anterior uroneural is fused with the terminal vertebra, 

 and there are no postterminal centra. Polymixia is the more primitive 

 of the two in all of the features mentioned. An examination 

 of the caudal skeletons of Hoplostethus, Myripristis, and Holo- 

 centrus indicates that various combinations of the Polymixia-Hop- 

 lopteryx types occur among berycoids (diagram 2). Thus Hoploste- 



Diagram 2. 



thus has the postterminal centrum and free uroneural of Polymixia 

 but the neural crest on the preterminal vertebra as in Hoplopteryx. 

 In Holocentrus the bone fusions are as in Hoplopteryx and there is 

 the neural crest on the preterminal vertebra as in Hoplopteryx, but 

 the first epural is so oriented as to give the distinct impression that it 

 has arisen from the neural spine of the preterminal vertebra. 



Among the Zeiformes the caudal skeleton of Antigonia (fig. 4A) 

 has the same basic structure as that of the percoid Serranus. In both. 



