192 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



The number of dorsal fin rays and the total number of gill rakers 

 proved to be the most critical characters in the separation of the 

 species. The interesting negative correlation between these two 

 characters accounts for the greater departure between the frequency 

 distributions of nobilis and lowei when a character index is formed by 

 subtracting for each individual specimen the total number of gill 

 rakers from the number of soft dorsal fin rays (table 3). Each of 

 these characters or their combination expressed as an index did not 

 completely separate all specimens of the three species, small overlaps 

 occurring among the distributions. The exact nature of these over- 

 laps and other reasons for the recognition of the species are discussed 

 under the description of each species. 



The number of anal fin rays may prove to be of value in separating 

 eastern and western populations of nobilis (table 5) . Four specimens 

 from Madeira had an anal fin ray count of 17 to 18, and five from 

 Cuba had only 16 rays. No doubt larger collections will reveal 

 some overlap, but this is sufficient indication that some differentiation 

 has occurred between these populations. This character is certainly 

 not very variable, judged from the nature of the modality of speci- 

 mens of lowei from Cuba and the Gulf of Mexico. I hesitate to name 

 this Cuban population because of lack of sufficient material and 

 because all three species are not completely separable in themselves. 

 The divergence of the characters in the various populations is quite 

 irregular and difficult to evaluate in respect to the real biological 

 differentiation. The single specimen from the Hawaiian Islands has 

 a higher anal ray count than the 25 specimens from Japan and the 

 Philippine Islands. Here again is a suggestion of population diver- 

 gence, but any reliable allocation of rank must await additional 

 collections. 



Evidence of differentiation between the Japanese and Philippine 

 populations of japonica is shown in the tabular data on the number 

 of pectoral fin rays, lateral line pores, and vertical scale rows and the 

 length of the chin barbel, but these require substantial verification. 



Geographic distribution 



The family has a global distribution in tropical and semitropical 

 waters where they are generally taken near some continental land mass 

 at deptlis of 150 to 350 fathoms, although some have been captured 

 in less than 50 fathoms. The species are considerably more widely 

 distributed than previously reported. The eastern Atlantic form, 

 nobilis, is reported for the first time from the western Atlantic. The 

 distribution of the western Atlantic form, lowei, is now more widely 

 known from the Gulf of Mexico and as far north along the Atlantic 



