FISHES. FROM ECUADOR AM) I'Krj—srAUKS. 779 



Family POEClLIID^l^. 



33. ORESTIAS PENTLANDI Valenciennes. 



This species is the best represented of its oonns in the collection. 

 Sixteen specimens, from 18 to 2(» cm. in length, were collected at Lake 

 Titicaca. 



(K pentlandl is an elongate form like O. einuci'l^ but ma}' be known 

 at sight by the short head, the small mouth and eye, the more com- 

 plete and smoother squamation of the anterior i)art of the body, and 

 the slender caudal peduncle. The form of the head and bod}' is more 

 symmetrical than in any Orestias here represented. The back is not 

 elevated to a blunt ridge; the temporal region is not laterally pro- 

 duced, and the anterior dorsal outline forms an unbroken curve to the 

 tip of the snout. 



Head 3| to 4^5 in length to base of caudal. Gape of mouth from 

 symphysis of premaxillaries to lower angle of mouth equal to diame- 

 ter of eye; width of mouth between lower angles li to 1^ times the 

 diameter of eye. Interorbital space evenly arched; 2 to 2i times the 

 diameter of eye. 



Series of scales above middle of sides from 55 to 00; 16 or 17 rows 

 between front of anal and front of dorsal. Side scaled to a level with 

 lower pectoral ray or a little below. Area in front of pectoral 

 usually naked, Init sometimes with a few scales. Top of head back 

 to behind eyes naked in some specimens, entirely scaled to slightly in 

 front, of eyes in others, or with a few scattered scales in still others. 

 ■ A narrow suborbital region always naked; scales of cheek extending 

 forward in vaiying degrees. 



Caudal peduncle narrow and less compressed than in any other 

 Orestias in the collection, though there is a large individual variation 

 in this respect. Width of caudal peduncle from 2 to 3 times in length 

 of head. 



34. ORESTIAS CUVIERI Valencienne . 



Four specimens from 22 to 24 cm. in length from Lake Titicaca. 



This species has a larger more oblique mouth, larger teeth, and a 

 longer head in proportion to the depth of the head, than any other 

 species of (hrstit/,^ here considered. 



Depth of head at occiput 1| to 2 in length of head. Length of gape 

 from symphysis of premaxillaries to lower angle of mouth i to i 

 times greater than diameter of eye, and equal to width of mouth across 

 its lower angles. Eye contained U to U times in distance fi-om its 

 anterior edge to mouth, or 2 times oblicjuely across top of snout to 

 union of premaxillaries, and If times in interorbital space. 



Ventral surface naked below a line extending obliquely downward 

 and backward from upper angle of gill opening to base of last anal 

 rav, or sometimes to lower caudal rays, leaving a narrow naked area 



