loo Field Columbian Museum — Zoology, Vol. VII. 



To U. S. Vice-Consul A. O. Wallace I am also much indebted for 

 many courtesies. Through his efforts I was enabled to get my outfit 

 into the country without duty or delay. His interest in the work 

 and the many personal favors granted are certainly much appreciated . 



The following notes and the accompanying figure are given to 

 explain the terms used in the descriptions: 



I. Head. 2, Snout. 3. Eye. 4. Premaxillary. 5. Maxillary. 

 6. Supplemental maxillary. 7. Mandible, or lower jaw. 8. Sym- 

 physis. 9. Cheek. 10. Preopercle. 11. Opercle. 12. Subopercle. 

 13. Spinous portion of dorsal fin. 14. Soft portion of dorsal fin. 

 15. Base of dorsal fin. 16. Pectoral fin. 17. Anal fin. 18. Ven- 

 tral fin. 19. Base of caudal fin (last vertebra). 20. Caudal fin. 

 21. Lateral line. 22. Depth of the fish. 23. Depth of caudal 

 peduncle. 24. Caudal peduncle. 



The PROFILE of the fish, unless otherwise mentioned, is the curve 

 from the highest point on the back to the tip of the snout. The 

 ORIGIN of the DORSAL or anal fin is the insertion of its first spine or 

 ray. 



Fishes in general, and especially those treated of in this paper, 

 breathe by means of gills, which are fine, hair-like projections (bran- 

 chje) , usually supported on the outer curves of cartilaginous or bony 

 arches known as gill arches; in the true fishes, the normal number 

 on each side is four. The gill rakers are a series of bony appen- 

 dages variously formed along the inner edge of the anterior gill arch. 



The GILL membranes usually serve to attach the gill covers to 

 the ISTHMUS, which is the thick, fleshy projection between the gill 

 openings. The branchiostegal membranes are attached to the 

 lower posterior portions of the gill covers; the cartilaginous or bony 

 supports of this membrane are the branchiostegal rays. 



The pharyngeal bones are behind the gills and at the beginning 

 of the CESOPHAGUs; in true fishes, they represent a fifth gill arch. 



The fins of fishes are composed of spines and rays, the former 

 being stiff, bony structures usually connected by a thin membrane ; 

 the rays are rather weak, jointed, cartilaginous structures, and are 

 also connected by a thin membrane. 



A cycloid SCALE has its posterior margin smooth; such scales 

 are usually found on soft-rayed fishes. A ctenoid scale has its pos- 

 terior margin rough or toothed ; such scales are characteristic of the 

 spiny-rayed fishes. 



The LENGTH of the body of the pish is measured from the tip of 

 the upper jaw to the base of the caudal fin or end of the last vertebra ; 

 the TOTAL LENGTH, from extreme ends of the fish. The lenotu of the 



