NO. 1468. FISHES FROM ECUADOR AND I'ERU—STARKS. 781 



naked areas are not separated from each other in this region. In one 

 or two examples a few scales or plates are irregularly scattered over 

 the lateral naked areas. Usually the naked areas extend back nearly 

 to opposite front of dorsal, but in some cases it does not extend more 

 than half that distance, and in others it is continued back along the 

 whole base of dorsal. Uusually the side is scaled to a level of the 

 lower pectoral ray, but sometimes the scales are absent below a line 

 curved downward between the base of the upper pectoral ray and the 

 front of anal. A triangular area of scales on cheek sometimes reaches 

 forward to below front of eye and sometimes ceases below middle of 

 eye; in either case the preorbital region may be entirely naked or with 

 a few scattered plates. A few of the specimens show traces of scat- 

 tered plates on the ventral surface, proba])l3' indicating their presence 

 on smaller specimens. The region in front of pectoral is naked and 

 nearly covered by the opercle. 



37. ORESTIAS LUTEUS Valenciennes. 



This species is represented by 6 specimens, from 122 to 112 mm. in 

 length, taken in Lake Titicaca at Chililaya, Bolivia. It is at once 

 known by the wide short head, having strong lateral angles. 



0. luteiis has a much shorter head than (J. alhu!<\ head 3 to 3^ times 

 in length of bod}^ to base of caudal. The height of head is greater, 

 though contained about the same luimber of times in the shorter head. 

 Width of head nearly equal to length of head. The back is much 

 more elevated than in O. alhus^ and there is a strong concave region 

 at each side of back. The elevation of back makes the dorsal outline 

 of head and nape more or less concave. Head as viewed from above 

 much produced lateralh^ at the temporal region, forming broadl}"- 

 rounded angles which taper quickh' to the narrow scarcely produced 

 snout. Mouth smaller than in O. alhus; not quite vertical; lower end 

 of gape scarcely extending below lower margin of eye. Scales more 

 regularl}^ placed and no naked area present on side of back; scales 

 covering side more completely below; naked area of belly not reach- 

 ing to level of lower pectoral ray. Opercle not extending so far over 

 region in front of pectoral, which region is nearly always thickly 

 covered with rough scales, though in one specimen it is naked. 



Family TYLOSURID^. 



38. TYLOSURUS JORDANI, new species. 



Head, 2f in length from tip of upper jaw to base of caudal. Depth 

 at occiput, twice diameter of eye. Eye, 3i in postorbital part of head; 

 interorbital space, 2| in same space. Eye and postorbital part of head 

 contained If times in mandible, measuring from eye. Dorsal, 13; anal. 

 14. Scales, 240. 



