46 BULLETIlSr 95, UNITED STATES NATIONAL MUSEUM. 



Color in alcohol : Back dusky olive ; a reddish brown lateral stripe, 

 bordered above with bluish, having the same form as in Chirostoma; 

 sides and belly lighter than back, yellowish, tinged with silvery; 

 fins dusky. 



Humboldt's conclusion that this is the common pejerey of the 

 Callao market, and that it occurs in large numbers in the ocean 

 within the limits of Peru is doubtless an error. That it is the 

 " pesce rey " reported to occur in the mountain lakes of Peru and in 

 Titicaca ; identified by Abbott • from specimens from Callao as 

 Pisciregia heardsleei ; by Cope on specimens from Arequipa as 

 Gastropterus arcTiaeus; by Steindachner, on specimens from the Rio 

 Tambo as Atheriiiopsls regius, and by Jenyns, on specimens from 

 fresh water at Valparaiso asAthernia microlepidota, appears to us to 

 be true. It is the " peje-rey de Eio," and not one of the salt-water 

 forms which belong to the genus Basilickthys. The greatest dis- 

 crepancy between Jenyns's description of A, microle'pidota and our 

 specimens is in the depth of the body. 



The following additional measurements of our largest specimen, 

 compared with those given bj^ Cope for G. archaeus^ are illustrative 

 of the closeness with which his description agrees with our speci- 

 mens. (The comparative measurements taken from Cope's figures 

 are placed in parenthesis following our own.) Head 4.T4 (4.74) in 

 total length; distance from tip of snout to origin of ventral fin, 2.67 

 (2.63), to origin of anal, 1.86 (1.85), to origin of second dorsal, 1.68 

 (1.73) ; tip of the pectoral reaching three-fourths of distance from 

 its base to base of ventral, and tip of ventral three-fifths of the 

 distance from its base to insertion of anal. 



As indicated by Steindachner, the presence of teeth on the vomer 

 appears to be largely an age character. An examination of examples 

 of At7ie7'i7iopsis californiensis, the species upon which this genus is 

 based, appears to bear out these conclusions. 



The scales are small, rather thick ; numerous verj'' distinct concen- 

 tric lines on their outer surface and from four to six well-developed 

 radiating striae on the basal half, rendering them readily distin- 

 guishable from the other peje-reys in our collection. 



Genus PROTISTIUS Cope. 



69. PROTISTIUS SEMOTILUS Cope. 



Protistius semotihis Cope, Proc. Acad. Nat. Sei. Phila., 1874, pp. 66-7; 

 Peruvian Andes, 12,000 feet; Proc. Amer. Philos. Sec, 1877, pp. 700- 

 701. — EiGENjiANN, Cat. Freshwater Fish. Trop. and Soutli Temp. Amer., 

 1910, p. 464. 



Cope ^ says that Gastropterus archaeus, which we consider synony- 

 mous with Atherinopsis regius, differs from this species in addition to 

 generic characters noted, " in the large number of soft raj^s, the 

 smaller eye, narrower interorbital space, etc." 



^ Proc. Amer. Philos. Soc, 1877, p. 701. 



