330 Bulletin 4j, United States National Museum. 



Family XXXVIII. ERYTHRINID^. 



Heterognaths with the skull above truncated behind, and the supra- 

 occipital contined to back of skull and carinated by a very slight vertical 

 crest. (Gill.) Adipose fin none; gill openings wide, the membranes 

 slightly united, free from the isthmus ; nostrils close together; teetli in 

 jaws well developed; pharyngeal teeth villiform; cheeks covered by the 

 suborbitals ; brain case inclosed above. Body elongate, belly rounded. 

 Dorsal fin short, of 8 to 15 rays. Carnivorous species, with short intes- 

 tines. Otherwise as in the Characinidiv. Fresh waters of South America. 

 Genera 4. Species about 20, one of them reaching our limits. 



a. Dorsal fin inserted in advance of anal, over ventrals ; gape very wide, little oblique ; both 

 jaws with strong canines ; maxillary with fine pectinate teeth ; teeth on palatines ; cau- 

 dal rounded ; lateral line developed. 

 h. Walls of air bladder normal ; teeth all pointed ; maxillary with a canine ; palatine teeth 

 with an outer series of enlarged teeth separated from the villiform teetli. 



Macrobon, 137. 



137. MACRODON, Muller. 

 (Trahikas or Aimaras.) 



Macrodon, Muli.er, Archiv., 308, 1842, (trahira = malahariais). 



Adipose fin none. Body elongate, the belly rounded ; gill openings 

 wide, the membranes slightly united, free from the isthmus ; nostrils close 

 together. Mouth very large ; snout pointed. Teeth well developed; an 

 outer series of palatine teeth enlarged and separated from the villiform 

 teeth ; a detached patch of teeth in front of palatines ; lower jaw with 

 canines anteriorly and laterally ; all the teeth pointed ; maxillary with a 

 canine anteriorly ; dentary process joined to the deutary at the symphy- 

 sis within the lateral canines and merging into the dentiferous ridge mid- 

 way between symphysis and posterior angle of dentary ; the pit formed • 

 behind the larger canine and the one behind the lateral canine filled with 

 numerous short conical teeth wliicli lie concealed in the muscles ; a deep 

 pit in the premaxillary for the reception of the larger dentarj^ canine ; 

 supratemporal plate single. Two species; large, voracious fishes, espe- 

 cially abundant in the Amazon region. {/laKpuc, long; oihv^, tooth.) 



a. Scales across back of tail from lateral line to lateral line eleven in number. 



MicnoLEPis, 550. 

 550. MACRODON MICROLEPIS, Gunther. 



D. 1-i ; A. 11 ; lateral line 43 or 44 ; scales a little smaller than in M. mala- 

 barieus, * there being 11 in a row across the tail above, from the lateral 



* This species, 3Iixcrodon malahricjis, is universally common throughout eastern South America, 

 from Trinidad and Rio Magdalena to Rio de la Plata. Its scales are nine from lateral line to 

 lateral line as above indicated. Its occurence north of the isthmus is not improbable. 



Concerning the n.ame of this species Professor Cope remarks: "Authors who think, with the 

 American Ornithologists' Uniuu, that scientific nomenclature may record errurinstead of truth, 

 call this well-known Soutli American species JH((crodcin nuihibaricus, because Bloch described it 

 first uu<ler that name, under tlie mistaken idea that it was a nativeof India." In the judgment 

 of the present writers, the law ot priority by which the first unpreoccupied name is 

 right, and all others wrong, a rule whicli tends to secure fixity of nomenclature, is more impor- 

 tant than any rule leading toward truthfulness or i>urism in the name itself. On this ground, 

 Ulacrotlan 7»nlahari<ns docs not mean a Marrodon from Malabar. It simply designates that Matio- 

 dunof which the earliest unpreoccupied binominal specific name is nialaharicus. The errors in 

 meaning in specific names deceive nobody and rarely cause inconvenience. 



