NTO. 5 MYERS AND WADE : ATHERINID FISHES 139 



4. THE PACIFIC SPECIES OF MELANORHINUS 



Genus MELANORHINUS Metzelaar 



Melanorhtnus Metzelaar, 1919, p. 38 (type by original designation M. 

 boekei Metzelaar).^ 



Mugilops Meek and Hildebrand, 1923, p. 271 (type by original designa- 

 tion M. cyanellus Meek and Hildebrand). 



This strange genus has been described as new twice, but we are not 

 aware that anyone has hitherto pointed out the identity of Mugilops with 

 Melanorhinus. There are two species. The smaller, Caribbean species, 

 Melanorhtnus boekei Metzelaar 1919, was described from St. Martin, 

 Dutch West Indies. Mugilops marinus Meek and Hildebrand 1923, 

 based upon a single specimen from Porto Bello, Panama, is almost cer- 

 tainly a synonym of boekei. The Pacific species is M. cyanellus. 



Metzelaar's description of Melanorhinus was published practically 

 simultaneously with Jordan and Hubbs' 1919 revision of the Atherinidae 

 and did not make use of that paper; and Meek and Hildebrand's work, 

 having been prepared previous to 1919, also did not utilize that revision. 

 Thus, the genus Melanorhinus has never been properly allocated in ac- 

 cordance with modern knowledge of the generic interrelationships of the 

 Atherinidae, and we have therefore redescribed it and attempted to indi- 

 cate its proper systematic position. 



In the 1919 revision of Jordan and Hubbs, Melanorhinus runs down 

 without trouble to the subfamily Atherinopsinae and possesses all the 

 characters of that subfamily save the important one regarding the posi- 

 tion of the pelvic fins. In Melanorhinus the pelvics are rather far for- 

 ward, under the middle or last third of the appressed pectorals, and their 

 origin is much closer to the upper angle of the pectoral base than to the 

 origin of the anal fin. In this but in no other important character Mel- 

 anorhinus approaches the subfamily Atherininae. Within the Atherinop- 

 sinae, Melanorhinus keys down without trouble through section "x^" of 

 Jordan and Hubbs' key, but with section "y" the genus is thrown out of 

 the key, since it agrees with neither of the alternatives. The head is cer- 

 tainly rather abruptly truncated, as in Eurystole, but the interorbital is 

 not flat and there is no preopercular spine. 



^Metzelaar described genus and species together, under the phrase: "Melano- 

 rhtnus boekei nov. gen. et spec." Under the International Code, this is taken as a 

 definite citation of genotype. 



