1883.] and the region farther East. 1019 
out numerous figures. In nearly every colony, however isolated, 
where individuals were at all numerous, I have rarely, if ever, 
found so persistent adherence to a single form as to admit of 
proper illustration by a single figure. 
Part II.—ANODONTA CALIFORNIENSIS IN A NEW LOCALITY. 
By the same mail which brought me the Indio parcel and Pro- 
fessor Davidson’s letter relating thereto, a note came to hand 
from Mr. Joseph F. James, custodian of the Cincinnati Society of 
Natural History, who, after reading my recent paper on the 
“Fresh-water Mussels,” etc., very kindly informed me that in 
June, 1880, he collected “ Anodonta californiensis in the little 
FIG. 3.—Anodonta californiensis Lea. 
Santa Cruz river, just outside of Tucson, Arizona.” This item of 
information gives quite an extension toward the east and south- 
east of the territory before known as tenanted by californiensis. 
The little Santa Cruz is a confluent of the Gila, and enters the 
latter at Gila Bend. The Gila is a confluent of the Colorado, 
joining the latter near Yuma. Tucson is about 250 miles east of 
Yuma, and following the course of the Gila to the mouth of the 
little Santa Cruz, thence southerly to Tucson, represents a sub- 
drainage area of which the length is much greater. 
An examination of a map of the region easterly and south- 
€asterly of the main stream of the Colorado and of the drainage 
the Gila, will enable one to take in ata glance the many 
Streams which are tributary to and finally merge in the Gila and 
Still later or afterward in the Colorado, which, together with the 
important fact furnished by Mr. James, warrant the inference that 
an exploration of the ramifications of the water channels of the 
Tegion included within their net-work, will show that the domain 
