PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 93 



to find specific differences. They are probably specimens which have de- 

 veloped under more favorable circumstances than are usually accorded 

 to the species. 



33. Enueacanthus obesus (Grd.) Gill. 



34. Enneacanthus gloriosus* (Holbr.) Jor. 



35. Enneacanthus eriarchus (Jor.) McKay, 



10. Genus Micropterus Lacepede. 



36. Micropterus salmoides (Lac.) Henshall iu "Book of the Black Bass" (advance 



aheetH) ^ Micro2>tenis jMUldtis Gill & Jor. 



37. Micropterus ilolomieu Lacepede = Micro/Jto'MS salmoides Gill. * 



Indiana University, 



Bloomington, Ind., March 10, 1881. 



A REVIEW OF TELM OENVS €EIVTIJBUS, SIVAIIVSOIV. 



By ROBERT RIDG^VAT. 



INTRODUCTION. 



The collection of the United States National Museum contains ex- 

 amples of all the known species of the genus Centurus, excepting C. hypo- 

 polius (Wagl.), C. ruhriventris Swains., and C. terricolor Berlepsch, the 

 two latter being of some what doubtful status. More or less coMfusion 

 has hitherto existed regarding the nomenclature of several of the Mid- 

 dle American forms, and it was the desire to clear awsby as much of this 

 confusion as possible that prompted the investigations upon which this 

 review is based, and which have led to the discovery of relationships 

 which were before quite unsuspected, at least by the writer. 



Of the fourteen forms treated of in this paper as sufficiently distinct 

 for definition, not more than six, or less than one-half, can be said to 

 be perfectly isolated, or to possess the requirements of perfectly distinct 

 species ; at least the abundant material which has been examined in this 

 connection proves beyond questiou the intergradatiou of four so-called 

 species, while it suggests more or less strongly the probability or possi- 

 bility of such relationship with regard to five of the remaining ten. 

 Those which appear to be unquestionably distinct are the three West 

 Indian species, C. radiolatus (Wagl.), C. svpereiliarin (Temm.), and C. 

 striatus (Mlill.), and three continental species, G. nrojjygialis, Baird, C. 

 hypopolius (Wagl.), and C. elegans (Swains.). Those which certainly in-, 

 tergrade, and are therefore to be united under one specific designation, 

 are G. aurifrons (Wagl.), G. santacruzi Bp., C. dvbius (Cabot), and G. hoff- 

 manni^ Caban , all of which are, however, strongly characterized geo- 

 graphical races or subspecies. The five forms of doubtful relationship 

 are (1) G. caroUnus (Linn.), which may ])ossibly grade into C. riibrivcntris, 

 but which in jjrobably distinct; (2) G. rubriventris {Sw.), with which I 



