Japanese Gempylidae — Matsubara and Iwai 
195 
KEY TO THE GENERA OF JAPANESE GEMPYLIDAE 
la. Caudal peduncle with a keel on each side; scales of body unique, each large scale 
being surrounded by a network of small pored tubular scales; lateral line greatly un- 
dulated, reaching nearly to both back and belly 
Lepidocyhium ( = Xenogramma; Lepidosarda) 
lb. Caudal peduncle without lateral keel; scales not surrounded by a network of small- 
pored tubular scales; lateral line not greatly undulated. 
2a. Abdomen keeled; skin spinigerous; lateral line obscure. Ventrals I, 5 Ruvettm 
2b. Abdomen not keeled; skin smooth; lateral line well- developed. 
3a. Ventrals well- developed, their rays I, 5; no detached finlets. 
4a. Body fusiform (depth about one fourth standard length); palatines toothed; 
lower lateral line running near lower contour of body; snout (Fig. 5C) not pro- 
jecting beyond anterior extremities of premaxillaries. 
5a. Vomer with 1 to 3 teeth on each side; the 2 lateral lines originating together 
at upper angle of gill opening; dorsal fin inserted behind upper end of gill 
opening; dorsal spines feeble and flexible; inner surface of gill raker at angle 
of first arch (Fig. 2 As) armed with 2 rows of minute spines; lining of buccal 
and branchial cavities black Neoepinnula 
5b. Vomer edentulous; the 2 lateral lines bifurcating below membrane between 
fifth and sixth dorsal spines; dorsal fin inserted above posterior margin of 
preopercle; dorsal spines rather strong and pungent; inner surface of gill raker 
at angle of first arch not armed with spines; lining of buccal and branchial 
cavities pale . Epinnula 
4b. Body elongate (depth about one tenth standard length); palatines edentulous; 
lower lateral line running along middle of body; snout (Fig. 5 A) projecting far 
beyond anterior extremities of premaxillaries Mimasea 
3b. Ventrals greatly reduced or absent; detached finlets always present. 
6a. Body greatly elongate (depth contained more than 12 times in standard length) ; 
detached finlets 5 to 7; ventrals minute, their rays I, 4 to I, 5, the soft rays hardly 
visible without aid of a lens; maxillary largely hidden under infraorbital mem- 
brane; gill raker at angle small, triangular; snout (Fig. 5B) projecting far beyond 
. tips of premaxillaries. Two lateral lines, both originating above angle of gill 
opening. Gempylus 
6b. Body moderately elongate (depth contained less than 9 times in standard 
length); detached finlets usually 2; ventrals absent or each represented by a 
single spine; maxillary wholly exposed; gill raker at angle T-shaped; snout 
(Figs. 5 D-E) projecting little or not at all beyond tips of premaxillaries. 
7a. Two lateral lines; ventral fins absent in adult .Rexea 
7b. One lateral line; ventral fins usually present. 
8a. A dagger-shaped spine followed by a minute free spine behind vent; lateral 
line straight; each pore in lateral line with short upper oblique branch only; 
scales nonimbricate Nealotus 
8b. No free spines behind vent; lateral line abruptly curved downward ante- 
riorily; each pore in lateral line behind the anterior curved part bearing 
short upper and lower oblique branches; scales imbricate Promethichthys 
