ORDER Y. 
PLECTOGNATHI. 
The premaxillar and maxillar hones are united into one continuous immovable bony piece. 
The internal skeleton is hut partly ossiffied. The opercular apparatus is hidden under a 
thickened skin. Branchial apertures small. The surface of the skin is either protected with 
enamelled scales, (ganoid,) else with asperities or spinous productions, characters by which 
these fishes are always easily distinguished from those of the other orders. The swimming 
or air bladder has no air duct in communication with the throat. 
Syn. — Plectognathes, Cuv. Tabl. elem. Hist. nat. Anim. 1798 ; Regn. Anim. II, 1817. 144 ; 2d ed. II, 1829 ; &, ed. illustr. 
Poiss. 333. 
Plectognathi, Bonap. Sagg. Distr. metod. Anim. Verterbr. 1831, 120.— Richards. Faun. Bor. Amer. Ill, 1836, 277.— 
DeKay, New Y. Faun. IV, 1842, 323.— Mull, in Wiegm. Archiv fur Naturg. 1845,1,134, & 137.— Storer, 
Synops. 1846, 239. 
The family of Ostracionidae , the third of this Order, has furnished as yet no representatives 
to the ichthyic fauna of our western coast, where, no doubt, some of them exist. Not being 
marketable fishes, they are no object of attraction except to naturalists, who, so far, have had 
but few opportunities to prosecute their explorations in that region of the country. 
A “sun-fish,” “head-fish,” or “moon-fish,” (Orthagoriscus) as sometimes called, has been 
observed off the harbor of San Diego, as I am informed by my friend Lieut. Trowbridge. 
The “moon-fish” may well be considered as the type of a fourth family ( Orthagoriscidae) 
amongst the Plectognathians. 
Family BALISTIDAE_, Bonap. 
The body is compressed, rather short and deep, covered with either large or small scales, or 
else with prickles, or granules. The snout is sub-conical and prolonged, terminated by a small 
mouth provided with a few isolated teeth. There are two dorsal fins, the anterior one often 
reduced to a single spine. The pelvic bone is prominent; the ventral fins being, however, but 
imperfectly developed. 
Syn. — Balislidae, Bonap. Sagg. Distr. metod. Anim. Vertebr. 1831, 120.'— DeKay, New Y. Faun. IV, 1842, 333.— Storer, 
Synops. 1846, 243. 
Balislini, Bonap. Catal. metod. Pise. Europ. 1846, 88.— Mull, in Wiegm Archiv fur Naturg. 1845, I, 134 & 137. 
Balistides, Dum. Ichthyol. analyt. 1856, 177. 
A species of this family was received during the early part of the present year from San 
Diego, California, where it was collected by A. Cassidy. The specimens having been mislaid 
in the moving of the Smithsonian collections from one end of the building to another a few 
months since, we are unable at present to refer it to its proper genus, and give any further 
description of the species, beyond stating that the specimens were of a jet black tint, with light 
(either white or yellow) margined fins. 
