ANNOTATED LIST OF THE SPECIES 351 
had only Corixid nymphs and adults; another with lower intestine packed with 
Corixid remains, the rest of the gut with plankton, mainly diatoms. 
Orestias miilleri. Cheese-like masses containing the tests of minute Clado- 
cera; no plant, no larger Crustacea. Some from Lake Poopo, 3.5 inches long, in- 
sects and fragments. From Moho, much red mud and grit; fragments of higher 
plants than algae; no shells. Intermittent rain with much mud entering through 
streams from the red sandstone formations of the region. 
Length of intestine 1.5 times length of fish. 
Orestias pentlandi. Many Cladocera, few algal filaments; mass of much finer 
material. Fishes more pelagic, intestine shorter than body, food finer than either 
of preceding. 
Orestias luteus. Intestine packed with Crustacea and great numbers of small 
Amphipods. The smallest specimens contained the largest prey. 
Orestias albus. Gastropod shells, many broken, but others entire. An older 
specimen, above 6 inches, with most of intestine packed with woody fragments, 
stems, leaves, ete., and a small portion of gut at anterior end filled with Gastropod 
shells. 
Intestine nearly 1.5 times body length. 
Zuniga, 1941, expresses the relative length of the intestine of several species 
as follows: O. pentlandii, vegetarian, 1.39; O. neveur?, piscivorous, 0.5; O. tschudii, 
crustaceans, 1.89; O. luteus, mollusks, 1.92. (From Biol. Abstr., article not seen 
by me.) 
THE SPECIES OF ORESTIAS 
As the synonymies will show there has been some confusion in the literature 
and numerous doubtful identifications, arising from the fewness and the imperfec- 
tion of specimens, the brevity and ambiguity of descriptions, and the inadequacy 
of the illustrations. My study began in the hope of reducing the number of 
species materially. Such a number of species in waters so intimately connected 
seemed doubtful. But, as a matter of fact, one by one they have turned up either 
in our collections or, in two cases, specimens borrowed. They appear not to have 
had the advantage of isolation during their long history, but perhaps we can explain 
the evolution of so many species, mostly in one drainage area, from the long series 
of more or less violent changes in the habitat, their rise from sea level to as much 
as 12000-13000 feet, diastrophic upheavals, volcanic activity, and the change from 
saline to fresh water. Perhaps the species of Orestias have been the most bom- 
barded of all fishes, with the greatest variety of external forces, some of which may 
have had genetic effects, even with our present understanding of genes. 
Confusion of species has also arisen from the choice of characters by which to 
separate them. The various authors have resorted to such characters as these: 
Finray counts which frequently overlap, never varying much 
Position and form of fins uniform for most species 
Teeth descriptions nearly identical 
Naked areas not consistently present or absent 
Depth of cleft of mouth hard to determine for lack of points of reference 
Striation of scales often not as given in deseriptions 
