160 U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



SUB-OKDER II. 



ACANTHOPTERYGII, 



The anterior portion of the dorsal fin is composed of spinous and inarticulated rays which, 

 however, constitute but one continuous fin with the soft and articulated rays. A few spinous 

 rays exist likewise at the anterior margin of the anal, and the external ray of the ventrals is a 

 spine also. The sides of the head are, generally speaking, smooth or spineless ; the edge of 

 the opercular hones being occasionally serrated. The scales are either ctenoid or cycloid in 

 structure. 



SYN. Pharyngognathi acanthopterygii, MULL, in Wiegm. Archiv fur Naturg. I, 1845, 136. 

 Jlcanthopterygii, LINN. Syst. Nat. ed. VI, 1748. Iconogr. Encycl. II, 1850, 204. 



Four families are on record in this sub-order, one of which, the Chromid, is without repre 

 sentatives in the collections upon which we are now reporting, but will be alluded to in the 

 Report of the United States and Mexican Boundary Commission. The Pomacentrid family has 

 yielded, so far, but one species along the Pacific coast of North America. As to the Labrids, 

 they appear to be more numerous, although we have had the opportunity of examining the 

 specimens of but one species. The Embiotocoids seem to compensate for the apparent scarcity 

 of the former and to constitute a prominent feature of the ichthyic fauna of the Pacific coast of 

 the United States. 



Family POMACENTRIDAE, Agass. 



The body is rather deep than elongated, and covered with scales ctenoid in structure or else 

 posteriorly ciliated. The lateral line is interrupted in its course. The dorsal fin is unique and 

 constructed as in Labroids. The lips are not fleshy, and the nostrils simple. The pharyngeal 

 teeth being card-like, the accessory gills, or pseudo-branchiae, comb-like, and a very small split 

 is to be observed behind the fourth branchial arch, the fourth gill having two unequal branchial 

 combs, the hind one being atrophied and quite small. An air bladder, but no air duct. The 

 stomach has a cul-de-sac, and the pylorus a few appendages. 



SYN. Pomacentridae, AGASS. inNom. Zool. Pise. 1847, Add. 5. 



Labroidei ctenoidei, MULL, in Wiegm. Archiv fur Naturg. I, 1843, 306 ; and, I, 1845, 136. 



In their external form and appearance the fishes of this family recall to mind the Squammi- 

 pennes, except the system of coloration, which is always of a more uniform cast. As an article 

 of food they are not esteemed, although served upon the table of the seacoast population. 



GLYPHISODON, Lacep. 



GEN. CHAR. Body compressed, sub-elliptical in profile, covered with large scales. Head moderate, scaly. Mouth small, 

 provided with maxillar teeth only, disposed upon a single row, closely set together, narrow, with a sharp and often emarginated 

 crown. Cheeks and opercular apparatus scaly also. Opercle and preopercle with serratures or spines. Two anal spines. Lateral 

 line not continued to the base of the caudal. 



g TN Glyphisodon, LACEP. Hist. nat. des Poiss. IV, 1802. Cuv. & VAL. Hist. nat. des Poiss. V, 1830, 442. STORER, 

 Synops. 1846, 79. 



