2(36 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Family LXVII. POMACENTRI DJE .~ The Demoiselles. 
Body short, deep, compressed, covered with ctenoid scales of varying size; lateral line wanting 
posteriorly; mouth small, usually with rather strong teeth, either conic of incisor-like; vomer and 
palatines toothless; nostril single on each side, nearly round; preopercle with its posterior edge largely 
free, serrate, or entire;- preorbital sheathing the small maxillary; dorsal fin single, with numerous 
strong spines, the spinous portion longer than the soft, which is similar to the soft anal, both fins scaly 
at base; anal spines 2; ventral fins thoracic, i, 5, the anterior rays longest, usually filamentous; a scaly 
appendage at base of ventral; lower pharyngeals fully united; branchiostegals 5 to 7; gills 3.5, the slit 
behind the last gill very small or obsolete; gillrakers rather long and slender; no labyrinthiform 
appendage; air-bladder and pseudobranchise present, well developed; pyloric coeca 2 or 3; gill- 
membranes free from the isthmus; vertebrae 12+14=26. Fishes of the tropical seas, similar in mode 
of life to the Clixtodonticke, feeding on small marine, animals and plants in the coral reefs. Most of 
them are too small to be used as food. They are very active in life, and the coloration is usually 
brilliant, sometimes changing much with age. The family shows strong affinities with the Labridse in 
gill-structures and pharyngeals. In other respects it approaches the Kyplwsidsc, while the unique 
character of the simple nostril is shared with the Cichlidx only, from ancestors of which group the 
Pomdcentridx are probably descended. 
a. Teeth conical, or villiform, not compressed. 
ft. Body deep; outer series of teeth conical and sharp; preopercle finely serrate Dascyllus, p. 266 
ftft. Body oblong; outer series t>f teeth bluntish; preopercle entii'e ■ Chromis, p. 267 
aa. Teeth not conical or villiform, somewhat compressed. 
e. Preopercle and preorbital serrate; teeth truncate or rounded '. Pomacentrus, p. 270 
cc. Preopercle and preorbital entire; teeth usually more or less emarginate Abudefduf, p. 271 
Genus 142. DASCYLLUS Cuvier. 
Preopercle and sometimes preorbital serrated; teeth small, villiform, in a narrow band, with an 
outer series of somewhat larger ones; dorsal fin with 12 or 13 spines, anal with. 2; scales of moderate size, 
in fewer than 30 transverse series; lateral line ceasing below the Soft dorsal fin; branchiostegals 5; 
gills 3.5; pseudobranchise present; air-bladder large; pyloric appendages 2 or 3. Coral reefs of the 
Pacific. 
Dascyllus Cuvier, Rftgne Animal, Ed. II, 91, 1S29 ( aruanus ); not DasciUus Latreille, Coleoptera, 1796. 
Tetradraehmum Cantor, Cat. Malay. Fishes, 241, 1850 ( apuanus ); substitute for Dascyllus, regarded as preoccupied. 
208. Dascyllus albisella Gill. Fig. 112. 
Head 3.35 in length; depth 1.5; eye 2.3 in head; snout 3.35; maxillary 3;' interorbital 2.75; D. 
xii, 16; A. ii, 15; scales 6-27-12. 
Body deep, short, greatest depth over base of pectoral; head much deeper than long, the anterior 
profile nearly vertical; snout short, vertical; mouth small, oblique; jaws subequal, protruding very 
little beyond anterior profile of bead; teeth in jaws with an enlarged outer series, conic, pointed; 
behind these several series of small teeth in each jaw 7 ; maxillary small, reaching little beyond anterior 
margin of orbit; interorbital width broad, convex; nostril circular, small; margins of preopercle 
and preorbital finely serrate; second dorsal spine longest, 1.4 in head; base of soft dorsal 2 in spinous 
dorsal, fourth ray longest, 1.2 in head; second anal spine 1.35 in head; seventh anal ray longest, 1.2 in 
head; caudal slightly emarginate, lobes rounded and upper longer than lower; pectoral pointed, upper 
rays longest, 2.1 in base of dorsal; ventrals large, pointed, 2.6 in body; caudal peduncle deep, 1.65 in 
head; scales large, ctenoid. The above description chiefly from an example (No. 543), obtained at 
Honolulu in 1889, by Dr. Jenkins. 
Color in life (Nos. 03445 and 03549), each scale with a blackish border and whitish base, except 
in the white area in middle of dorsal part of body, where dark borders of each scale are almost absent; 
nuchal spot blue when present; all fins dark, almost black, except the whitish scales on dorsal fin. 
One example (No. 03355) shows genera) color whitish, blue darkest on head and breast; scales 
enveloping bases of dorsal and anal whitish blue; snout and anterior part of head dark brownish blue; 
dorsal pale bluish, blackish toward tip; caudal, anal, and ventrals bluish black; pectoral pale blue; 
iris bluish brown. 
