1854.] 197 



blackish. Beneath dull yellowish ; external margin of ventrals blackish. Dor- 

 sal fins olivaceous; extremity of caudal blackish with a lighter margin. 



Collected by Dr. A. L. Heermann,at San Francisco, Cal., while attached to the 

 Pacific Railroad Survey under Lt. R. S. Williamson, XL S. A. 



Abstract of a Report to Lieut. Jan. M. Gilliss, IT. S. iV., ?/po?i the Fishes col- 

 lected during the IT. S. iV. Astronomical Expedition to Chili* 



By Charles Giraru. 



PERC1D.E. 



Genus PERCICHTHYS, Girard. 



Body oblong or elongated, compressed, covered with scales of medium develop- 

 ment, finely ciliated upon their posterior margin. Snout rather thick and blunt, 

 overlapping slightly the lower jaw ; card-like teeth on the jaws ; velvet-like 

 teeth disposed upon a transverse band in front of the vomer, and upon a narrow 

 band along the palatines, sometimes only towaids the anterior extremity of these 

 latter bones. Tongue smooth. Upper surface of head, suborbitals and posterior 

 dilatation of the upper maxillary, covered with scales as well as the cheeks and 

 opercular apparatus. Suborbital and preopercle serrated. Opercle provided 

 with a spine. Branchiostegals six or seven in number. Two dorsal fins conti- 

 guous at their base. Insertion of ventral fins immediately beneath the base of 

 pectorals. Anal fin provided with three spiny rays. 



1. Percichthys chilensis, G. Perca trucha, Gtjich. in Gay, Hist, de Chile, 

 Zool. II. 1848, 146, Ictiol. Lam. I. bis. fig. 1. Snout subcorneal, obtuse ante- 

 riorly, and slightly overlapping the lower jaw. Mouth well developed. Posterior 

 extremity of upper maxillary fetching the vertical of the centre of the pupil. 

 Limb of preopercle conspicuously serrated. Exterior margin of sub- and inter- 

 opercle inconspicuously so. Soft portion of an'al deeper than the height of the 

 second dorsal. Caudal moderately emarginated posteriorly. Branchiostrgals 

 seven. Ground color yellowish ; upper regions covered with brownish or blackish 

 diffused spots. 



Inhabits the fresh waters of Chili. 



2. Percichthys melanops, G. Mouth of moderate size ; posterior extremity 

 of upper maxillary reaching the vertical of the anterior rim of the orbit. Pala- 

 tine teeth occupying but a small area towards the anterior extremity of these 

 bones. Opercular spine not very conspicuous. Branchiostegals six. Ground 

 color whitish, minutely and densely dotted with black ; dots crowding upon the 

 middle of the scales under the shape of a central blotch, giving to the whole fish 

 quite a dark hue. 



Caught in a tributary of the Rio de Maypo, Chili. 



Genus PERCILIA, Girard. 



General physiognomy percoid, body compressed. Two dorsal fins contiguous 

 at their base, broadly separated in their outline. Mouth rather small or else of 

 medium size; jaw T s subequal. Small conical teeth upon the maxillaries, and a 

 few card-like ones upon the front of the vomer, none on the palatines. Tongue 

 smooth. A few minute spines along the limb of the preopercle. Opercle without 

 any spine. External edge of suborbitals, sub- and interopercle not crenated. 

 Branchial aperture of either side continuous under the throat. Branchiostegals 

 five or six in number. Scales quite large, and posteriorly ciliated. Cheeks and 

 opercular apparatus scaly; top of head nearly smooth and naked. Suborbitals 

 and maxillary scaleless. Insertion of ventrals behind the base of pectorals. 

 Caudal posteriorly subcrescentic. 



3. Percilia gillissi, G. Snout short and rounded, mouth small ; posterior 

 extremity of upper maxillary corresponding to the vertical of the anterior rim 



