NEW FISHES FROM WESTERN PACIFIC — BOLIN 327 



angle of interopercle; these spines frequently difficult to see but 

 readily located by touch in alcoholic specimens. No other spines 

 on head. Pores of head well developed; those on suborbitals divided 

 into two almost equally prominent series bordering the suborbital 

 chain dorsally and ventrally; anterior pore of the mandibular series 

 unpaired, opening on the median ventral surface of the symphysis. 

 Gill membranes broadly united, free from isthmus. Brancliiostegals 

 6. Teeth in moderately broad, vilKform bands on premaxillaries, 

 dentaries, vomer, and palatines. No slit behind the last gill. Gill 

 rakers in the form of short tubercles. 



Origin of first dorsal directly over or very sUghtly behind dorsal 

 end of gill opening; first two spines with a,pproximate bases. Second 

 dorsal separated from first by a narrow but definite interspace. 

 Origin of anal under f.rst, second, or third dorsal ray. Pectorals 

 extending to perpendicular from first or second anal ray. Pelvic 

 base very shghtly behind lower end of pectoral base; fin of 1 spine 

 and 2 rays, the inner one the longer. Caudal sUghtly roimded. 

 Anus in front of anal origin at a distance about equal to diameter 

 of pupil, located just anterior to a, very small, bluntly conical, genital 

 papilla. Sides of body with 1, 2, or 3 longitudinal bands of large 

 ctenoid scales, each band only one scale in width. No cirri present. 



Remarks. — It is difiicult to estimate the exact degree of relation- 

 ship of the three fishes comprising this genus. However, the fact 

 that Stlengis misakia has progressed farthest in the reduction of 

 scales, and that in tliis species the pores of the lateral line system on 

 the head have remained small and those of the mandibular series 

 becom.e encircled by small supernumerary openings, wliile in the 

 other two species they have become markedly enlarged and remained 

 simple, indicates that 8. misakia is the most isolated form. While 

 this species was probably the first to spUt from the ancestral stock, 

 the pronounced differences occurring in the other two species suggest 

 that they were derived from a branching of the primitive line soon 

 after the splitting off of S. misakia. 



The preopercular armature, the ventral fins, and the structure of 

 the scales indicate that this genus is most closely related to Icelinus 

 Jordan, of the western coast of North America. 



KEY TO THE KNOWN SPECIES OF THE GENUS STLENGIS 



a'. Sides of body armed with a single band of scales; main pores 

 of mandibular series surrounded by small supernumerary 



openings misakia 



a^. Sides of body armed with 2 or 3 bands of scales; pores of mandi- 

 bular series simple. 

 6'. Sides of body with 2 bands of scales; anal fin with 10 or 11 



rays distoechus 



h". Sides of body with 3 bands of scales; anal fin with 14 rays osensis 



