FISHES. 237 



pectorals, and their tips extend further backwards. Their spiny ray is well developed, and 

 the central soft ones bifurcate three times upon their length. The pectorals are short, and 

 rounded when expanded, composed of slender rays which bifurcate only twice. 



Br : V— VI; D IX. 11 ; A III. 8 ; C 4. I. 8. 7. I. 3 ; V I. 5 ; P 14. 



The scales are large, provided posteriorly with slender and filiform serratures. They are 

 higher than long, anteriorly subtruncated, and rounded upon the other sides of their outline. 

 Four longitudinal rows are observed between the anterior dorsal and the lateral line, and about 

 twelve rows beneath, between the latter and the middle line of the belly. They diminish in 

 size towards the occiput and nape, as well as towards the inferior surface of the body. The 

 largest may be seen upon the middle of the flanks. The upper surface of the head is nacked 

 and perfectly smooth. Small scales esist on the cheeks, and somewhat larger ones on the 

 opercular apparatus. The suborbitals and the maxillary are scaleless. The lateral line, in 

 which there are about thirty-five scales, from the upper part of the opercle to opposite the mid- 

 dle region of the second dorsal fin, constitutes a depressed and occasionally somewhat undula- 

 ting arch ; then runs nearly straight towards the base of the caudal fin. 



The ground-color assumes either a light reddish or reddish brown hue. The head, dorsal 

 region, and sides of body and tail, are irregularly blotched with blackish or deep brown — the 

 blotches being the result of an accumulation of minute dots. The lower surface of the head 

 and throat are sown over with similar dots sometimes disposed in irregular streaks. The 

 ground-color of the fins is light yellowish, the rays made blackish by crowded dots ; the pecto- 

 rals and ventrals less so than the dorsals, caudal, and anal. 



Inhabits the Kio de Maypu ; specimens were obtained from an affluent of that river, in the 

 vicinity of Santiago. 



Plate XXIX, fig. 5, represents the profile of Fercilia gillissii, size of life, 

 fig. 6 is an outline, viewed from above, 

 fig. T, a scale of the dorsal region, 

 fig. 8, a scale of the lateral line, 

 fig. 9, a scale of the abdominal region. - 



Figs. 7, 8, and 9 are magnified. 



FAMILY OF ATHERINIDiE. 



The study of this family, heretofore composed of the single genus Atherina, has led us to 

 establish several new genera in which the rather numerous species are grouped according to 

 several structural peculiarities which, though apparently inappreciable on account of their 

 moderate development, are not to be altogether overlooked. 



The genus Atherinopsis is to receive such species in which there are no palatine teeth^ with 

 both jaws equal, and the snout more or less rounded. 



Atherina menidia, Linn., and Atherina notata, Mitch., will find a place in this genus along- 

 side with Atherinopsis calif orniensis, Grd. 



The genus Basilichthys will be characterized by the protrusion of the upper jaw beyond the 

 lower one. There are no teeth on the palate. 



To this must be referred : 



1". Atherina microlepidota, Jen., from the fresh waters^of Chile, described further on. 



2°. Atherina latidavia, Guv. and Val.,* from the coast of Chile, and easily distinguished by 

 its large scales and its broad silvery lateral band. 



3°. Atherina argentinensis, Cuv. and Val., observed at the mouth of the Eio La Plata and 

 Bay of Maldonado, and commonly known as Pescadilla del rey. 



*Hist. Nat. des Poiss. X, 1835, 473. 



