4. uMinuNA. 27'i 



nent spines at the angle of the ])ra)opcrc\ihim. There are about nine 

 spinous teeth along the posterior limb, gradually becoming .sniullcr 

 at the upper part of the margin. Tho operculum has a very deej) 

 and semicircular notch posteriorly, between two points, the ujjper 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 subopercxdum are elongate. 



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

 more or less regular cavities ; a i)art of its posterior margin is in- 

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

 differ from those of Scia^na umazonica. 



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

 the other Scicenldoe. 



Tliere are ten abdominal and fifteen caudal vertebra', the length 

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

 ] 1 : 20. The first four vertebra) are much more voluminous than 

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

 with deep lateral grooves (at the abdominal surface); the abdominal 

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

 from the seventh vertebra. The ribs of the third, fourth, and Jifth 

 are broader than the others. Epipleurals well developed. The first 

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

 as the first eight vertebra) together, and attached to the ha^mals of 

 the eleventh and twelfth vertebra?. 



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

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

 lower pharj-ngoal bones are partly cardiforra, those of the upper 

 partly villiform, partly conical molars. 



2. Micropogon trifilis. 



Milll. ^ Trosch. in Schomh. Riis. Brit. Guyana, iii. p. 622. 

 D. 10 I ^. A. |. L. lat. 50. 



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. 4' T.) 



Coast of Guiana. 



4. UMBRINA*. 



Umbrina, Car. liegne Anim. ; Ckv. S,- J^al. v. p. 171. 

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

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

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



* 1. Umbrina unclulata, Girard, Proc. Acad. Naf. Sc. Philad. 1854, p. 148, and 

 U. S. Faaf. R. B. Exped. FMes, p. 101.— California. 

 2. — phalfBna, Girard, Proc. Acad. Nat. Sc. Philad. \85S, p. 107.— Texas. 

 VOL, II. T 



