^°l89o'"'] PROCEEDINGS OF THE NATIONAL MUSEUM. 357 



poiuts, iu a baud ou eacb jaw ; the external pleiirodont or attached to 

 the surface of tlie jaws. 



Lips very thiu ou the upper jaw, obsolete ou the lower. 



Tongue moderate. 



Suborbitals weW developed; the preorbital rather high, with a free 

 inferior margin and covering the sides, connected suturally by two pro- 

 cesses with the palatine arch of the jaws ; the succeeding bones narrow 

 but with wide subocular exi)aumous ; the posterior connected with the 

 preoperculum. 



Opercular apparatus normally develoi)ed ; preoperculum large and 

 extending downwards, with a free inferior as well as posterior margin ; 

 ojjercM^MWi well developed ; suboperculum continuous with and bordering 

 the operculum; interoperculum narrow and concealed under the infe- 

 rior margin of the preoperculum. 



Branchiotremes ami)le and continuous below, but restricted in front 

 by the brauchiostegal membrane, which is broad and but slightly 

 emarginated behind, being continuous between the rami of the jaws 

 and confluent iu front with the skin of the deutary, and separated on 

 the sides from the preoperculum by a groove or furrow. 



BranchiostegaJs iuyolved in thick skiu and only discernible on dissec- 

 tion, seven on each side. 



DorsaJis divided into a longer anterior ])ortion with ten to twelve 

 robust heteracauth si)iues and a posterior shorter ])ortion composed of 

 branched rays. 



Analis confined to the posterior half of the body, with an anterior 

 well differentiated portion having four large heteracantli spines, and 

 with a soft portion nearly corresponding to the soft i)ortiun of the 

 dorsal. 



CaudaUs well developed, emarginated or with a nearly entire poste- 

 rior margin, with fourteen branched rays, and with few raylets. 



Pectorales novmaUy inserted, rather small, with the rays branched and 

 rapidly decreasing downwards. 



Ventralcs thoracic, inferior, and approximated ; each with a spine and 

 five branched rays decreasing inwards, covered on the external surface 

 with small scales; closing at the base in a rudimentary excavation 

 formed by folds of the skin ; without any axillary appendages. 



REMARKS. 



The Scatophagidm will be thus seen to be very trenchantly separated 

 from the Chcctodontoiilea as well as all other families, so far as their 

 characters are known. The Chcetodontoidea are well distinguished by 

 the abbreviated anterior vertebriie and their peculiar relations, as well 

 as by the inferior insertion of their ribs— characters reenforced by 

 Bumei'ous others.* 



* The characteristics of the Chwtodontoidea were indicated by the author iu 1883 

 (Proc. U. S. Nat. Mus., Y. 5. p. fi.^/.)). 



