4. TJMBEINA. 273 



nent spines at the angle of the prfeoperculum. There are about nine 

 spinoxis teeth along the posterior limb, gradually becoming smaller 

 at the upper part of the margin. The opemdmn has a very deep 

 and semicircular notch posteriorly, between two points, the upper of 

 which is obtuse ; the lower is slightly prominent, and forms the 

 termination of a slight crest at the interior side of the operculum. 

 The inter- and suboperculum are elongate. 



The suprascapula has several thin bony bars, forming four or five 

 more or less regular cavities ; a part of its posterior margin is in- 

 distinctly denticulated. The other bones of the humeral arch do not 

 differ from those of Sciama amazonica. 



The base of the skuU is very much swollen and globular, as in 

 the other Scicenidce, 



There are ten abdominal and fifteen caudal vertebra, the length 

 of the former portion of the column being to that of the caudal as 

 11 : 20. The first four vertebrae are much more voluminous than 

 the following; the fifth has a pair of prominent longitudinal ridges, 

 with deep lateral grooves (at the abdominal siu'face); the abdominal 

 surface of the sixth is concave ; the haemal spines form a closed arch 

 fi'om the seventh vertebra. The ribs of the thii-d, fourth, and fifth 

 are broader than the others. Epipleui'als well developed. The first 

 interhaemal is of moderate strength, composed of three ridges, as long 

 as the first eight vertebrae together, and attached to the htemals of 

 the eleventh and twelfth vertebrae. 



The dentition is formed by viUiform bands, and there is an outer 

 series of rather longer teeth in the upper jaw. ' The teeth of the 

 lower pharjTigeal bones are partly cardiform, those of the upper 

 partly villiform, partly conical molars. 



2. Micropogon trifilis. 



Miill. 8^ Trosch. in Schonib, Heis. Brit. Gtiyana, iii. p. 622. 

 D. 10 I i.. A. I-. L. lat. 50. 



I 20 



Only three minute barbels under the chin. Snout swollen, with- 

 out any pores or lobes ; the diameter of the eye is one-third of the 

 length of the head, and one-half larger than the interspace between 

 the eyes. Caudalis rhomboidal ; the second anal spine nearly as 

 long as the first soft ray. {M. 3f T.) 



Coast of Guiana. 



4. UMBRINA*. 



Umbriua, Cur. Regne Anim. ; Cur. S,- Val. v. ji. 171. 

 Body oblong ; muzzle convex, with the upper jaw overlapping the 

 lower ; a short barbel under the mandibular symphysis. Two dor- 

 sals, the first with nine or ten flexible spines ; the anal fin with one 



* 1. Umbrina imdiilata, Girard, Froc. Acad. Nat. Sc. Philad. 1854, p. 148, and 

 U. 8. Pacif. R. R. Expe.d. Fishes, p. 101.— CaUfornia. 



2. phalsena, Grirard, Proc. Acad. Nat. Se. Philad. 1858, p. 167. — Texas. 



VOL. II. T 



