A NEW GENUS AND SPECIES OF EEL FROM THE 

 PUERTO RICAN DEEP 



By earl D. REID 



Diz'isifln of Fishes, U. S. A\itioiial Museum 



Further study of the fishes obtained by the First Johnson-Smith- 

 sonian Deep-Sea Expedition to the Puerto Rican Deep has revealed 

 an interesting form of deep-sea eel. The specimens are very close 

 to Xenomystax tntcidaiis Alcock, from the Arabian Sea, but differ 

 notably in the more posterior insertion of the dorsal fin, in the posi- 

 tion of the vent, in the broader isthmus, and in color. From 

 X. atrarius Gilbert, from off the coast of Ecuador, our specimens are 

 distinguished by the position of the posterior nostrils, by the propor- 

 tionally longer body, and by the reduced number of branchiostegal 

 rays. Our material differs from X. rictus Garman, in addition to the 

 above-mentioned characters, in having the origin of the dorsal fin 

 above the first third of the pectoral length. 



Since the position of the posterior nostrils and the reduced num- 

 ber of branchiostegal rays are considered of generic rank, it becomes 

 necessary to propose a new genus for the accommodation of Xenomy- 

 stax tntcidaiis Alcock and my new species. 



Family MURAENESOCIDAE 

 PARAXENOMYSTAX, n. gen. 



Genotype. — Paraxcnoinystax hidcntatits. n. sp. 



Body scaleless, long, tapering, the caudal strongly attenuated pos- 

 teriorly. Vertical fins well developed, continuous with the lanceolate 

 caudal fin. Pectoral fins well developed, narrow, long, and pointed. 

 Origin of dorsal above or slightly behind base of pectorals. Gill 

 openings wide, crescentic, fold of upper membrane descending in front 

 of pectoral base. Branchiostegal rays 8, long, and recurved upward 

 around angle of opercle. Mouth with wide lateral cleft to behind eye. 

 Maxillary little expanded posteriorly. Teeth all slender and sharp, 

 conical, those on the outer margin of jaws in bands and depressible. 

 Maxillary and mandible wath a longtitudinal edentulous groove ex- 

 tending the entire length of the bone and dividing the bands of teeth 

 into two portions. Posterior nostrils slitlike before eye. Lower jaw 



Smithsonian Miscellaneous Collections, Vol. 91, No 31. 



