378 U-S. NATIONAL MUSEUM BULLETIN 202 Vol. 2 



is immature. The females lack barbels, except a rudimentary one 

 occurs on the large female. 



The holotype of Petroscirtes azureus Jordan and Scale has been 

 re-examined. It has the white edge all the way around the rear margin 

 of the caudal fin as in the other three specimens at hand ; the dorsal 

 rays are XI,27; anal 11,28; pectoral 14; pelvics 1,3; there are 7 or 8 

 barbels on under side of head; and the teeth in the lower jaw nmnber 

 25. 



Aspidontus tractus Fowler (Proc. Acad. Nat. Sci. Philadelphia, 

 p. 170, pi. 7, 1903) from Zanzibar, with a black bar on the pectoral 

 base, is a distinct species. 



ASPIDONTUS FLUCTUANS (Weber) 



Petroscirtes fhiduans Weber, Notes Leyden Mus., vol. 31, pp. 146-147, 1909 



(type locality, between Gebe and Fau Islands; Banda Sea) ; Siboga-Expeditie, 



vol. 57, p. 541, fig. 113, 1913 (on types). 

 Petroscirtes quadrimaculatus Kendall and Goldsborough, Mem. Mus. Comp. 



Zool. vol. 26, No. 7, p. 329, pi. 7, fig. 1, 1911 {tjv^ locality, Arno Atoll. 



Marshall Islands; Papeete, Tahiti, Society Islands). 



SPECIMENS STUDIED 



Bikini Atoll; 2 stations, 3 specimens, 41 to 42 mm. in standard length. 



Rongerik Atoll: 1 station, 2 specimens, 41 and 42 mm. 

 Arno Atoll: 2 lots, 2 specimens, 35 and 41 mm., USNM 65981, paratype, and 

 USNM 65980, holotype, of P. quadrimaculatus Kendall and Goldsborough. 



Description. — Dorsal rays IX or X,30 to 32; anal 11,27 or 28; 

 pectoral 14; pelvics 1,3; no branched caudal fin rays; no tentacles; 

 small or incisorlike teeth in lower jaw about 15 to 21 and upper jaw 

 about 18 to 21; 2 small canines each side of upper jaw, 1 enlarged 

 canine each side of lower jaw; gill opening extending down in front of 

 bases of 9 or 10 pectoral rays. 



Head (tip of anteriormost projection of snout to rear of fleshy 

 gill cover) 4.0 to 4.1; greatest depth 6.0 to 6.1; longest pectoral ray 

 7.4 to 7.5; snout tip to anus 2.1; all in standard length. Eye 3.7 

 to 4.0; snout 3.4 to 3.7, postorbital part of head 2.0 to 2.1; least 

 depth of body 3.1 to 3.3; greatest depth 1.5 to 1.6; length from snout 

 tip to rear of mouth or rictus 4.2 to 4.3; width of gill opening 3.6 to 

 3.9; longest dorsal spine 2.3 to 2.4; all in length of head. Bony 

 interorbital space 0.9 in eye. Eye 1.0 in snout. 



Lips without folds; lower canines greatly enlarged, those of upper 

 jaw small, usually 2 on each side, mostly concealed by lips; teeth in 

 both jaws, firm, immovable, of equal size; dentigerous edge of both 

 jaws transversely rounded; mouth nearly terminal; rounded snout 

 projecting a little in front of mouth; both anterior and posterior 

 nostrils with low tubes, the anterior one longest and with a short 

 tentacle arising from the posterior edge, distance between each pair of 



