FISH FAUNA OF LAKES OF SOUTHEASTERN OREGON, 77 
water forms, widely differentiated species, many of which constitute peculiar genera 
characteristic of the basins in which they occur. They are Orthodon microlepidotus, 
Lavinia exilicauda, Mylopharodon conocephalus, Pogonichthys macrolepidotus, Leu- 
ciscus crassicauda, and Rutilus symmetricus, of the Sacramento; Chasmistes brevi- 
rostris, Chasmistes stomias, Chasmistes copei, and Deltistes luxatus, of the Klamath; 
Pantosteus jordani, Acrocheilus alutaceus, Rhinichthys dulcis, Couesius greeni, Leucis- 
cus caurinus, Columbia transmontana, and others, of the Columbia. Each species 
included in this series is limited in its distribution to a single river basin and it is 
not represented in another by a closely related form. A third series, consisting, 
like the second, of fresh-water species, differs notably, however, in that each of its 
members is represented in at least one other than the native basin by a closely related 
form. To make this statement more clear a single example may be cited. There 
is in each of the three basins a large-scaled catostomid— Catostomus occidentalis in 
the Sacramento, C. snyderi in the Klamath, and C. macrocheilus in the Columbia. 
These resemble one another so closely as to be diflicult to distinguish, and their 
characteristics are such as point directly to the probability of a common origin of 
the three forms. The species which may be assembled in this series, and which 
appear to bear out the general observation concerning its members, are here 
tabulated. 
Sacramento. Klamath. | Columbia, 
Catostomus occidentalis. .............-.-. Catostomus snyderl............ ....| Catostomus macrocheilus, 
Catostomus microps. Catostomus rimiculus. . F - Catostomus catostomus, 
Rutilus thalassinus 
ee ae era eta ea Wh aS ocig dials d's'a.a:s1e'e woin eww a's Leuciseus bicolor. .. Leuciscus balteatus, 
Agosia nubila carringtonl........ : Agosia klamathensis. . Agosia nubila carringtont. 
Rutilus bicolor. ......... . | Rutilus columbianus, 
PeVVOUOGNGUUA/RTANGIN> + cseecls sorcery s-aceslensevcoten<s eet Cth ke | Ptychocheilus oregonensis. 
Turning again to the Oregon lake system, it will be found, as is shown in the 
more detailed part of this paper, that the immediate affinities of its fish fauna are 
with those species of the Sacramento, Klamath, and Columbia rivers which, except 
the trout,” have been assembled in the third series of the above scheme. Moreover, 
the bond of relationship indicated by a similarity of structure of the representative 
forms in the different basins is so strong as to leave little doubt of a community of 
descent. 
Cope traced a close affinity between the Oregon lake (including also Goose and 
Klamath lakes) and the Lahontan systems, and such a relationship no doubt exists. 
It is only relative, however, as an examination of the representative species will show. 
Rutilus oregonensis differs from Ff. olivaceous in important dental characters which 
are of at least subgeneric value. Between Catostomus warnerensis and C. tahoensis 
the difference is not so great, yet the bond of relationship appears to be no closer than 
it is between C. warnerensis and allied forms in the Columbia and Sacramento rivers. 
Although the status of the described forms of Agosia is not well understood, the 
examples from the Oregon lake system much more closely resemble the form known 
as A. klamathensis than that found in the Lahontan system. 
The present study has not only shown what is believed to be the true relation- 
ships of the Oregon lake fishes, but it has also pointed out an affinity existing 
aThe relationship of the trout is in line with the other species, the same form being found in the Sacramento, 
Klamath, and Columbia rivers. 
