85 



Subgenus Dicrolene, Goode & Bean. 



Dicrolene, Goode and Bean, Bull. Mas. Comp. Zool. X. 1883, p. 202, and Oceanic Ichthyology, p. 337 : Giinther 

 Challenger Deep-Sea Fishes, p. 107 : Jordan and Evermann, Pishes N. Amer. III. 2522. 



Pteroidonus, Giinther, Challenger Deep-Sea Fishes, p. 106 : Goode and Bean, Oceanic Ichthyology, p. 337. 

 Paradicrolene, Alcock, Ann. Mag. Nat. Hist., Nov. 1889, p. 387. 



Differs from Neobythites only in having the lower pectoral rays, to the num- 

 ber of 6 to 10, prolonged, and more or less isolated from each other and from 

 the rest of the pectoral fin, as free filaments. This one character is, in any case, 

 insufficient to justify the separation of Dicrolene from Neobytldtes ; but the 

 character itself is variable, for not only in the young of one species, but also in 

 the adults of another species, the lower pectoral rays are, for a considerable 

 distance, united to one another and to their pectoral fin by membrane. 



Key to the species of Dicrolene. 



I. Pectoral filaments free and independent in the adult : no circumscribed 

 cross-band on tlie tail : — 

 . 1. Twenty-seven rows of scales between the dorsal fin and the vent ... D. intronigra. 

 2. Tliirty-four rows of scales between the dorsal fin and the vent ... D. multifilis. 



II. Pectoral filaments inter-connected by membrane in their basal moiety : a 

 broad black cross-band, involving also the dorsal and anal fins, on the 

 posterior third of the tail ... ... ... ... ... D.nigricaudis. 



65. Dicrolene intronigra, Goode & Bean. 



Dicrolene intronigra, Goode and Bean, Bull. Mus. Comp. Zool. X. 1883, p. 202, and Oceanic Ichthyology, p. 338, 

 fig. 297 A, B : Giinther, Challenger Deep Sea Fishes, p. 107 : Vaillant, Exp. Sci. Travaillear et Talisman, Poissons, 

 p. 258, pi. xxiii. fig. 2. 



Paradicrolene Vaillanti, Alcock, Ann. Mag. Nat. Hist. (6) VI. 1890, p. 297. 



D. circ. 100. A. circ. 85. P. 18-19/8-9. V. 2. 



(1) Length of head one- fifth the total or less: (2) greatest height of the 

 body equal to the length of the head without the snout. 



( 3) Snout broad, rounded, hardly overhanging the upper jaw, as long as the 

 eye, but hardly equal to the width of the inter-orbital space. Nostrils rather 

 large and far apart, one being in front of the eye, the other near the edge of the 

 snout. 



(4) Major diameter of eye two-ninths to one-fourth the length of the head. 



(5) Upper jaw decidedly more than half the length of the head, overhanging 

 the lower jaw. Villiform teeth in broadish bands on the jaws and palatines 

 and in a narrow A-shaped patch on the vomer : none of the teeth enlarged. 



(6) Opercular spine a long sharp style : three spinules at the angle of the 

 preoperculum. 



(7) Gill-rakers on the outer side of the first branchial arch numerous and 

 of good length. Each pseudobranch consists of two small filaments. 



