1090 Bulletin //, United States National Museum. 



This genus includes those Teuihididw which have the tail armed with 

 a sharp, autrorse, lancet-like, movable spine; strong, fixed, incisor teeth; 

 ventral rays, I, 5, and usually 9 spines in the dorsal fin. The numerous 

 species are found in all tropical seas ; herbivorous fishes, living about coral 

 reefs ; the adult protected by the murderous caudal spine, which grows 

 larger with age. (rsvOii, the Squid, Lolifio; substituted by Liunteus for 

 Grouow's name, Hepatua, for no evident reason.) 



a. Caudal spine small; species pale, barred with black. teiostegus, 2104. 



aa. Caudal spine strong; species not pale, barred with black. 



6. Dorsal and anal without yellow streak, widened behind on dorsal and anal. 



c. Outline rhomboid, the depth IJ in length, color brown, washed with deep 

 blue. C.ERULEUS, 2105.- 



ec. Outline ovate, the depth about 2 in length; color brown, never blue. 



d. Caudal simply lunate. hepatus, 2106. 



dd. Caudal deeplj- emarginate. 



e. Upper lobe of caudal not filamentous. crestonis, 2107. 



ce. Upper lobe of caudal produced in a filament, bahianus, 2108. 



6&. Dorsal and anal with a yellow streak broadened behind ; a flesh-colored crescent 



under eye. aliala, 2109. 



•2104. TEUTHIS TRIOSTEGUS (Liunneiis). 



Head 3! ; depth l^ ; eye 21 in snout. D. IX, 23 ; A. Ill, 21. Body ovate, 

 anterior profile gently curved, most convex over eyes ; snout somewhat 

 produced, concave above. Dorsal fin moderate, anterior spines more or 

 less concealed in the slvin, the longest spines about 1^ in snout, the soft 

 rays shorter; first anal spine very short, the third longest, about equal to 

 longest dorsal spines; soft portion of anal about as high as the third anal 

 spine; caudal slightly lunate, the lobes but little produced; pectorals 

 about as long as head; ventrals as long as snout. Color in life, dark 

 oreenish or slaty above, with yellowish cloudings; chin, belly, throat, 

 and a narrow strip along base of anal, white; vertical fins dusky; anal 

 with a narrow white margin ; pectorals plain ; ventrals white on under 

 surface ; sides with 5 black bars each about as wide as pupil, the first, 

 beginning just in front of the branchiostegals, extends upward and back- 

 ward across cheek, through eye and to median line of Itack, where it meets 

 its fellow from the other side; the second begins at front of dorsal fin and 

 extends downward to base of pectoral from which point it is continued 

 downward in a narrower line beginning on base of ])ectoral and endiug 

 just above base of ventral; the third begins near base of sixth dorsal 

 spine and extends across side to belly at a point midway between anus 

 and beginning of aual fin; the fourth begins on base of first dorsal ray 

 and extends to first anal ray; the fifth begins at base of seventh dorsal 

 ray and extends across side to base of fifth anal ray; a black spot on 

 upper side of caudal peduncle. Pacific Ocean; very abundant about 

 rocky islands from New Zealand and Australia to the Hawaiian Islands 

 and the Revillagigedos; not yet found elsewhere in American waters ; our 

 specimens from Clarion and Socorro islands, (trlostegus, rpeii, three j 

 drey 00, to cover.) 



