138 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



First closal spiue If in snout, theuce almost evenly increasing in lieiglit 

 to tlie sixth, which is 2f in head, seventh to eleventh about equal, 

 twelfth 2 in Lead ; the soft portion of dorsal higher than spinous, its 

 highest rays 1^ in head, its margin rounded. The filiform elongation of 

 the fifth ray is broken off. Caudal truncate. Middle rays of anal 

 longest, giving a bluntly pointed outline to the fin ; second anal spine 

 not as long as third and scarcely stronger, 2J in head. Ventrals If in 

 head. Pectorals 1^ in head. Scales finely ctenoid. Fins scaled as usual. 



Preopercle crenulate at the angle and on lower margin. 



Color, in spirits, pale olivaceous with dark and black markings ; five 

 dark lines ascend obliquely from shoulder-girdle to dorsal, seven similar 

 ones ascend obliquely from anal meeting the anterior lines at a right 

 angle ; above the seven lines and running parallel with them are about 

 four wider greenish-brown bands, which anteriorly describe a right angle 

 ascending to the dorsal, this part of the wide bands thus running par- 

 allel with the lines on front part of body, the ground color between 

 these bands being of a sulphur yellow. A black band descends perpen- 

 dicularly across the eye, narrower and fading out above, a third wider 

 than orbital diameter below the eye, the bands of the two sides, extend- 

 ing across the interopercle, meet at the isthmus. A black oval spot near 

 the margin on the sixth, seventh, eighth, ninth, and tenth soft rays of 

 dorsal. Between the posterior spines of the dorsal the connecting mem- 

 brane is narrowly margined with black, the soft dorsal edged with black 

 to the twenty-third ray. The extreme edge of caudal fin is white, ante- 

 rior to which is a narrow space of gray margined with black, then a 

 dull-yellow lunate space equal in width to both the other marginings ; 

 the base of the caudal being grayish leaves this lunate space outlined 

 by a gray line, the dusky ground color covering the anterior two-thirds 

 of the length of the fin. And with a thread-like line of black near its 

 margin. Pectorals and ventrals plain. Peritoneum dusky. 



One fine specimen (26831), 7^ inches long. 



20— ACANTHUEUS TEIOSTEGUS (L.) Bloch. & Schn. 



Cli(eto(lon triostegus Liuii. Syst. Nat. i, 403; Brouss. Icbthj*. fig. and description, 1782; 



Gmel. Syst. Nat. 1246, 1788 (Pacific & Indian Oceans). 

 Cha'todon couagga Lac. iv, 727, 1802. 

 Acanthurus zebra Lac. Hist. Nat. Poiss.iii, pi. 25, fig. 3, 1802, iv, 160, pi. 6, fig. 3, 1802; 



C. &, V. Hist. Poiss. X, 197, 1835 (Isle de France, Sechell^s, Marianna, N. 



Zealand, Oulan, Society and Sandwich Islands). 

 Acanthurus triostegus Bl. & Schn. Syst. Ichthy. 215, ISOl (Pacific and Indian Oceans); 



Blkr. Enum. Spec. Pise. Archip. Indie. 75, 1859 (name only); Bll^r. Conspec. 



Molncc. Cognit. 12 (Buro, Amboyna, Ternate, Ceram, Archip. Mohicc. ; name 



only); Blkr. Bijd. Visch. N. Gnin^e, 4, 10 (name only); Blkr. Zes. Bijd. Visch. 



Sumatra, 5, 21 (Kauer, Trnssan, Padang, Ulakau, Sibogba, Priamam) ; Blkr. 



Twaalfde Bijd. Visch. Celebes, 2 (name only) ; Blkr. Beschrij. Visch. Amboiua, 



6 (name only) ; Blkr. Beschrij. Manado Makassar, 4,20 (Manado; name only); 



Blkr. Achtste Bijd. Visch. Amboina, 5, 20 (name only) ; " Blkr. Verhand. Batav. 



Genootsch, sxiii, Tenth. 13; Jeuyns, Voy. Beagle, Fishes, 75"; Gthr. Cat. 



