TRIRADIATED ACANTHURUS. 381 



nated : a strong spine at the base of the pectoral 

 fins. Tail slightly lunated : spine on each side 

 very strong and sharp : native of the Indian and 

 American seas : in the British and Leverian Mu- 

 seums. 



TRIRADIATED ACANTHURUS. 



Acanthurus Triostegus. A. fusco-virescens, fasciis quatuor 



transversisfuscis, cauda utrinque aculeata. 

 Greenish-brown Acanthurus, with four transverse dusky bands, 



and a spine on each side the tail. 

 Chaetodon triostegus. Lin, Chaetodon, &c. Seb. 3.t.25.f.4, 



Length about four inchest shape rhombic-ovate : 

 head suddenly sloping : general colour pale greenish 

 brown, marked with four narrow transverse brown 

 stripes or bands : scales very small : gill-covers un- 

 armed : gill-membrane three-rayed : in the throat 

 three small rough bones : teeth crenated : tail 

 lunated : spine on each side very strong. Native 

 of the Indian seas. 



GUARDED ACANTHURUS. 



Acanthurus Harpurus. A. corpore rhombeo-ovatofusco, squami* 



minutissimis, cauda utrinque biaculeata. 

 Rhombic-ovate, brown Acanthurus, with extremely minute 



scales, and two spines on each side the tail. 



Shape rhombic-ovate : length about six inches : 

 colour dusky brown, without any variegation : 



