less rudimentary, inserted on the S^l^ 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- -- — 



gatus). 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 

 water of the tropicalindo- 

 pacific. 



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. 



Fig. 9. Shoal of Aeolisats strigaUis (Gthr.) 

 in attitude of swimming. Tliey are represented 

 as if swimming from right to left. (After Willey). 



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. Centiiscns p. 21. 



