METHODS 



Measurements and counts were made accord- 

 ing to the methods of Hubbs and Lagler (1958), 

 except for the following: depth of head was 

 measured just posterior to orbit ; length of orbit, 

 as longest horizontal distance between fleshy 

 margins of orbit; width of bony interorbital, 

 above vertical midline of eye; depth of body, 

 from origin of first dorsal spine vertically to 

 ventral surface of body; and lengths of caudal 

 fin lobes, from middle of origin of caudal fin to 

 distal ends of longest rays. The last ray of dorsal 

 and anal fins was counted as one when branched 

 to the base. 



Pelvic fins and caudal-fin lobes with long fila- 

 ments were difficult to measure. Some of the fila- 

 mentous fins were measured by stretching them 

 out along a meter stick. Other measurements 

 were made with needlepoint-micrometer-dial 

 calipers. When the two pectoral and two pelvic 

 fins were of unequal length, the longer fin was 

 measured. 



Where possible, gill rakers (including rudi- 

 ments, when present) on the anterior gill arch 

 and pectoral-fin rays were counted on the right 

 side, pored lateral-line scales on the left side. 



Most specimens had lost many scales and con- 

 sequently accurate counts of pored lateral-line 

 scales were made on fewer than a third of those 

 examined. Approximate counts of lateral-line 

 scales were recorded for a number of specimens. 

 Accurate and approximate counts of scales are 

 combined in table 1 and distinguished in table 2. 



GENUS SYMPHYSANODON BLEEKER 



Symphysanodon Bleeker, 1878: 60 — also p. 26 

 in author's undated reprint — (type species 

 Symphysanodon typus Bleeker, 1878, by orig- 

 inal designation — by virtue of the name 

 typus) . 



Propoma Giinther, 1880: 39 (type species Pro- 

 poma roseum Giinther, 1880 [= Symphysano- 

 don typus Bleeker, 1878], by monotypy). 



Rhyacanthias Jordan, 1921 : 646 (type species 

 Rhyacanthias carlsmithi Jordan, 1921 [= 



Symphysanodon typus Bleeker, 1878], by orig- 

 inal designation) . 



Snout relatively blunt. Anterior ends of pre- 

 maxillaries incised, forming a conspicuous notch 

 — the notch receiving the anterior ends of the 

 dentaries. Extreme dorsalmost margin of maxil- 

 lary covered by very narrow suborbital with 

 mouth closed. Mouth terminal ; mandible inclined 

 dorsally when mouth closed; jaws about equal. 

 A bony elevation (which may be pronounced) on 

 posterodorsal surface of dentary. Two narial 

 openings on each side. Pseudobranchise present. 

 Gill arches four, a slit behind the fourth. Pre- 

 maxillary with small teeth— usually larger an- 

 teriorly; premaxillary notch toothless. Dentary 

 with small teeth usually extending from bony 

 elevation almost to the symphysis ; teeth on and 

 near bony elevation usually larger; usually a 

 number of relatively large, exserted teeth at an- 

 terior end of dentary — these teeth fitting into 

 notch in upper jaw when mouth closed; sym- 

 physis toothless. Teeth, when present, on vomer, 

 palatines, and pterygoids small; no teeth on 

 tongue. Dorsal fin continuous and not incised at 

 junction of spines and soft rays. Opercle with 

 two flattened spines, the ventral one longer and 

 more prominent. Scales ctenoid; posterior part 

 of snout, interorbital, preorbital, suborbital, 

 maxillary, ventral surface of mandible, pre- 

 opercle, interopercle, opercle, and subopercle with 

 scales; dorsal and anal fins without scales, but 

 with scaly sheaths at their bases ; large modified 

 scales associated with pelvic fins, just dorsal to 

 each pelvic spine (axillary scales) and in the 

 ventral midline between the pelvic fins some- 

 what overlapping their anteromedial borders. 

 Lateral line gently curved beneath the dorsal fin ; 

 cephalic lateral-line system well developed. Pro- 

 nounced sexual dimorphism in at least one species 

 (and probably in two). 



Dorsal-fin rays usually IX, 10. Anal-fin rays 

 III, 7 or 8. Pectoral-fin rays 15 to 18. Pelvic-fin 

 rays I, 5. Principal caudal-fin rays 17 (9 + 8). 

 Vertebrae 25 (10 precaudal + 15 caudal). Bran- 

 chiostegal rays 7. Gill rakers well developed, 

 rather long and slender, 9 to 14 + 22 to 29 — 

 total on anterior gill arch 31 to 42. Pored lateral- 

 line scales 43 to 54. 



326 



U.S. FISH AND WILDLIFE SERVICE 



