26 Dr. Richardson's Contributions to 



second dorsal spine being represented as no stronger than the 

 rest, and its filamentous tip as being very little prolonged. 

 Russell's specific character also states "spina anali unica" 

 whereas in our example of filament l osus the second and third 

 spines are both very conspicuous and longer than the soft rays 

 of the fin, the second being the strongest one, and but just 

 perceptibly shorter than the third. 



Both the anal and dorsal spines are much compressed. The first 

 dorsal spine is very short, the second is as broad again in the direc- 

 tion of the axis of the fish as any of the others, and its filamentous 

 tip, which in Mr. Gilbert's specimen is broken off, is stated in the 

 1 Histoire des Poissons ' to be long enough to reach to the caudal 

 fin. The lateral line is strongly marked on scales smaller than the 

 others. Rays.— D. 9|10; A.3|7 ; P. 15 ; C. 17}; V. 1|5. 



The colours have of course faded in the dried specimen, but the 

 scales still exhibit much pearly and silvery lustre with strong reflex- 

 ions when moved in the light. Above the level of the pectoral each 

 scale has a deep steel-blue bar along its middle producing about 

 nine longitudinal lines, the intervals and all the under parts being 

 silvery. There are about five of the blue lines with four silvery ones 

 above the lateral line. 



Dimensions. inches, lines. 



Length from intermaxillary symphysis to tip of caudal 6 9 



■ base of caudal .-. 5 3 



anal fin 3 10 



ventrals 2 2 



dorsal 2 2 



pectorals 1 8 



■ — edge of gill-flap ...... 1 7 



centre of eye 9£ 



Diameter of eye 6 



Depth of caudal fork 1 



Height of third dorsal spine 1 



■ of third anal spine 8£ 



Chaetodon sexfasciatus (Nob.), Six-banded Chaetodon. 



Specimen in the British Museum. 



The Chaetodon s with vertical bands do not appear to be nu- 

 merous. Two species only are described in the 6 Histoire des 

 Poissons,' one of them (striatus) with five bands, and the se- 

 cond with eight (octofasciatus). A third species with bands 

 (chrysurus) is mentioned in the ' Zoological Proceedings' for 

 1833 (p. 117)? as existing in the seas of the Mauritius. Its 

 bands are also eight, but they are angular in the middle. Mr. 

 Gould brought a six-banded species from Western Australia, 

 which is now in the British Museum. 



Its profile, including the dorsal and anal fins, and excluding the 

 parts before the eye and half the trunk of the tail with its fin, is nearly 

 orbicular. The profile of the head is concave, and thus causes the 



