scale at PLO two or three times PLO in size, the tissue in short, irregular, somewhat 



vertical lines D. malayanus 



22b. PLO always, VLO usually, nearer lateral line than to pectoral and pelvic bases. SAO2 

 and AOa, usually above, rarely on, a line through PLO and VLO. Dn of males much 

 enlarged, that of females small. Luminous scale at PLO somewhat rectangular, about as 



large as pupil, the tissue convoluted D. garmani 



23a. PLO usually much nearer pectoral base than to lateral line; VLO always nearer lateral 

 line than to pelvic base. A line through SAOi.j usually passes before SAO;,. Dn not 

 expanded to over nasal rosette. Anterior end of frontal supraorbital bone produced into a 

 strong, forward-directed spine. Luminous scale at PLO somewhat triangular, half or 

 more the size of orbit, the tissue convoluted near center but in closely spaced, more or less 



parallel lines near margin D. splendidus 



23b. PLO and VLO about on same level, both slightly nearer lateral line than to pectoral and 



pelvic bases, or about midway between. No AOp over anal base 24 



24a. PLO and VLO much nearer lateral line than to pectoral and pelvic bases. AOai often over 

 A0a2. Dn of males (only) expanded to over nasal rosette. Luminous scale at PLO slightly 



larger than pupil, the tissue in short, nearly vertical lines D. schmidti 



24b. PLO and VLO only slightly nearer lateral line than to pectoral and pelvic bases, or about 

 midway between. AOai usually over or distinctly behind AOa^. Luminous scale at PLO 

 triangular, slightly larger than pupil, the tissue in closely spaced, wavy lines radiating 



away from PLO D. signatus 



25a. Ant present. Inner row of teeth of lower jaw much enlarged, curved, rather widely and 

 evenly spaced. PLO a little above level of VLO and nearer lateral line than to pectoral 

 base. VLO slightly nearer pelvic base than to lateral line. SAOa and Pol at lateral line. 

 Pre progressively more widely spaced. Luminous scale at PLO about half the size of pupil, 



the tissue in long, vertical lines D. fragilis 



25b. Inner row of teeth of lower jaw not notably enlarged 26 



26a. Head considerably longer than deep 27 



26b. Head short, about as deep as long 32 



27a. Ant much elongated and narrow, extending back under supraorbital bone to near hind 

 margin of pupil. Dn small; Vn separated from Dn and extending under orbital rim to 

 about midpupil. PLO much nearer pectoral base than to lateral line. VLO about midway 

 between pelvic base and lateral line. Luminous scale at PLO large, roughly triangular, 

 nearly filling space between PLO and pectoral fin, the apex rounded, the tissue finely 



convoluted D. adenomas 



27b. Ant round or somewhat triangular 28 



28a. SAO;, and Pol two to threeof their diameters below lateral line 29 



28b. SAO3 and Pol at lateraHine 30 



29a. Orbit about 3 in upper jaw. Dn small, not extending over nasal apparatus or to near 

 median ethmoid crest. Gill rakers short and heavy, total rakers 19 (18-20). Luminous 



scale at PLO about half the pupil in size, the tissue convoluted D. coeruleus 



29b. Orbit about 2 in upper jaw. Dn large, extending over nasal apparatus nearly to median 

 ethmoid crest. SAOi low, slightly above level of VO5. First AOa elevated to above level of 

 SAO2. Gill rakers long and slender; total rakers 25-26 (24-27). Luminous scale at PLO no 

 more than twice the size of PLO, the tissue in wavy lines radiating from a point on 



anterior margin of scale D. rolfbolini 



30a. Vn elongated posteriorly, extending below hind margin of pupil. PLO much nearer lat- 

 eral line than to pectoral origin. Luminous scale at PLO about half the pupil in size, the 



tissue nearly horizontally striated, the scale thin and fragile D. chrysorhynchus 



30b. Vn not elongated posteriorly but barely extending under anterior margin of pupil. PLO 



about midway between lateral line and pectoral origin 31 



31a. Least depth of caudal peduncle 54% (52-55'7r) of length of peduncle. Body rather robust, 

 its depth at pectoral origin 24% (23-25) of SL. Total gill rakers 28 (26-29). Luminous scale 



101 



