PHILIPPINE MACROUROID FISHES GILBERT AND HUBBS. 445 



margin of the suborbital region, is dark, showing through the thin 

 outer wall of the cavity; the rami of the mandibles are dark. The 

 gular membrane has a ground color of silvery white, especially on the 

 sides where covered by the mandibular rami, but is darkened by 

 punctulations or a diffused dark expansion of the chromatophores. 

 The branchiostegal membranes are dusky ventrally, but, together 

 with the opercular membranes, are margined with light on their sides, 

 just behind the submarginal blackish area of the branchial cavity, 

 which shows through the opercles to the exterior; the roof of the 

 branchial cavity is dark; the walls of the buccal cavity are light; 

 the parietal peritoneum is blackish, underlain with silvery. The 

 vertical fins and the pectoral are dusky ; the dorsal spine is blackish ; 

 the ventral fin rays are light, with dusky tips and dusky bases in 

 some specimens. 



C. thompsoni differs from C. argentatus in much the same manner 

 that C. quincunciatus does; the scales are larger, being in but four 

 series, instead of five or six, between the lateral line and the origin 

 of the second dorsal fin ; the underside of the head, 1 and the antero- 

 lateral region of the snout above, are scaled, instead of being mostly 

 naked ; and the gular membrane is punctate, rather than transversely 

 striate. From botlvof the other species G. thompsoni differs in the 

 more posterior position of the front of the premaxillaries, which lie 

 below the posterior nostril, instead of below the middle of the large 

 nasal fossa. Further differences between C. thompsoni and C. quin- 

 cunciatus consist chiefly in the various proportions. These differ- 

 ences are tabulated in the following comparison ; further differences 

 between thompsoni and argentatus are also indicated. 



Comparative tabic showing the differences in certain proportions between the 

 species of the subgenus Quincuncia. 



Anus to ba^e of ventral in head 



Anus to isthmus in head 



Preoeular length of snout in head : 



Preoral length of snout in head 



Width i:f snout at anterolateral angles in distance anterior 



thereto 



Orbit in snout 



Orhit in postorbital 



Interorbital in postorbital 



Suborbital in postorbital 



Distance between occipital ridges in interorbital 



Ma illary in head 



Tectoralfin in head 



Outer ventral ray 



Second ventral ray 



Barbel in postorbital 



C. quincunciatus. 



2.4 to 3. 2 

 1.32 to 1.6 



2.3 to 2. 55 



2.8 to 3. 3 



1.1 to 1.3 



1.6 to 1.9 

 1.3 to 1.7 

 1.3 to 1.5 



2.7 to 3.1 



2.9 to 3. 3 



3.3 to 3. 7 



2.4 to 2. 65 

 3.0 to 3. 2 

 3. 75 to 4. 2 

 2.3 to 3.0 



C. thompsoni. 



2.7 to 3. 5 



1. 6 to 2. 

 2.1 to 2. 2 



2. 22 to 2. 35 



1.4 to 1.55 



1.8 to 1.95 



1.05 to 1.2 

 1.23 to 1.4 

 2.5 to 3.0 



2.4 to 2.65 



4. 05 to 4. 35 



3. 05 to 3. 3 



3.6 to 4. 3 

 4. 65 to 5. 1 

 3.4 to 4. 6 



1 With the exception of the mandibular rami, which are nearly naked in thompsoni, 

 but scaled in quincunciatus. 



