SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 91 



AI. obtusirostra 



Body photophores (BO) 14 or 15, in 

 a single straight, continuous series. 



Ventral photophores (VO) 4, dis- 

 tinctly separated from BO series ; 

 small in size * and slightly separated 

 from each other. 



Supra-anal photophores (AO) small 

 and separated from each other by 

 distances much greater than their 

 own widths;* 13 + 4 in number; 

 the first four forming an upward arc. 



Eye with iris wholly dark. 



Teeth of maxillary and premaxillary 

 small ; directed forward very 

 slightly. 



M. disjunct a 



Body photophores (BO) 14, with a 

 disjunction between the twelfth and 

 thirteenth. 



Ventral photophores (VO) 4, scarcely 

 separated from the BO series by 

 pelvic base ; large * and placed 

 tightly together. 



Supra- anal photophores (AO) large 

 and separated from each other by 

 distances distinctly less than their 

 own widths;* 14 + 3 in number; 

 the first two slightly elevated. 



Iris dark except for a silvery segment 

 below. 



Teeth of maxillary small, interspersed 

 with enlarged teeth ; all teeth of 

 upper jaw strongly directed for- 

 ward, those of the premaxillary ex- 

 pansion and of anterior part of 

 maxillary pointing almost straight 

 forward. 



Family TRIACANTHIDAE 



The discovery of a second genus and species of this family in the 

 Western Hemisphere by the Johnson-Smithsonian Deep-Sea Expedi- 

 tion is exceptionally interesting. Hollar dia hollar di was described by 

 Poey in 1861 from a single specimen cast ashore near Havana. Poey's 

 type, a dried skin in good condition, is still the only example known, 

 and it is here figured (pi. i, fig. 2) for comparison with the new 

 genus. The two specimens referred to H. hoUardi by Breder in 1925 

 are considered below to belong to a distinct species. 



In attempting to work out the relationships of the new form, it was 

 found useful to prepare a table of the genera, and since there has 

 been no recent attempt at a revision, my notes are presented in the form 

 of a key followed by brief remarks on the genera. In describing the 

 new gentis and preparing the synopsis, I have been fortunate in having 

 at hand examples of all the described recent genera, from the col- 

 lections of the United States National Museum. 



I am unable at present to correlate either of the two fossil tria- 

 canthid genera, Acanthoplenrxis Agassiz ° and Marosia^ de Beaufort' 

 with the recent forms. Both seem near Triacanthus. 



' See Woodward, Cat. Foss. Fish. British Mus., part 4, p. 566, 1901. 

 Jaarb. Mijnw. Ned.-Ind., vol. 54, pt. i, p. 142, pi. 5, fig. 5, 1926. 



