Proceedings of 

 the United States 

 National Museum 



SMITHSONIAN INSTITUTION • WASHINGTON, D.C. 



Volume 115 1964 Number 3493 



A REVISION 



OF THE CARCHARHINID SHARK GENERA 



SCOLIODON, LOXODON, AND RHIZOPRIONODON 



By Victor G. Springer 



Introduction 



The purpose of this paper is to revise the genera Scoliodon, Loxodon, 

 and Rhizoprionodon. The most recent studies allocate all the species 

 included in this report to a single genus, Scoliodon, and it is for this 

 reason, together with their superficial resemblance to each other, that 

 the three genera are treated together. While these genera do not 

 seem to form a natural group, judgment of their relationships is de- 

 ferred until the other genera of the family Carcharhinidae are more 

 completely known. 



Among the three genera, Scoliodon is quite distinct from the other 

 two and easily distinguishable from all other Carcharhinidae. Loxodon 

 and Rhizoprionodon perhaps are closely related, and it is possible that 

 the two subgenera under Rhizoprionodon should be elevated to generic 

 status. Differences separating the genera, as they are here recog- 

 nized, are presented in the key, and their characteristics are dis- 

 cussed under the respective generic headings. 



The characters previously used in assigning the species herein to a 



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