less rudimentary, inserted on the 8th plate and coalesced along 



their inner margin; they have a spinous and 4 soft, but un- 



articulated and unbranched rays, which may be prolonged in 



males (of Aeoliscus stri- ~- _ 



gains). The pectorals are 



inserted on the middle 



of the depth of the body 



at a considerable distance 



from the head. Their 4 



pterygials are stout but 



short. The cleithrum is 



suspended from the post- 



temporal which is sutu- 



rally united to the skull. 



Part of the cleithrum is 



covered by the dorsal 



cuirass; the scapula with 



a large foramen; post- 



cleithrum ( postclavicle ) 



and supracleithrum (su- 



praclavicle) present. Four 



branchiostegals. Four 



complete pectinate gills ; 



pseudobranchia large. 



Small fishes living in 

 small shoals in shallow 



Fig 



of 



(Gthr>) 



water Of the tropical mdo- in attitude of swimming. They are represented 

 pacific. as if swimming from right to left. (After WILLEY). 



About the position of 



these fishes in water, which one of us has observed as a normal 

 one, it is said by other observers that it is a vertical one, 

 with the head upwards or according to still an other observer 

 with the head downwards. 



Key to the genera of Centriscidae. 



1. Dorsal spine with a movable spinous ray at its end. Inter- 



orbital space striated, convex, without longitudinal groove. Aeoliscus p. 20, 



2. Dorsal spine without a movable spinous ray at its end. Inter- 

 orbital space convex or with a groove continued to the 



crown of the head, which is striated ............. Centriscus p. 21, 



