204 General Notes. [ February, 
A. cygnea, of which Dr. Lea has listed no less than one hun- 
dred and six synonyms. As A, anatina is shown to be buta 
varietal or conditional aspect of A. cyguea, therefore these alleged 
American species are regarded as belonging to A. cygnea. 
Dr. Stearns also includes in this identity with A. cygnea, the 
West American forms known heretofore as A. nuttallana, A. 
qwahlamatensis, A. oregonensis, and A. californiensis ; these ate 
traceable to Cygnea, through its Anatina aspect or condition, a 
well as through others of the many varieties of Cygnea, which 
_have led to the extensive synonymy above referred to. 
Specimens of A. anatina, from Regent’s park, London, laid 
upon valves of A. californiensis, so-called, from Owen’s river, Cali- 
fornia, he found to agree exactly in incremental lines and in final 
or peripheral outline. 
He further shows how specimens of A. cygnea, at a certain stage 
of growth, would, if collected at the time when the shell had 
reached said stage, have been called Anatina, but not having been 
collected until said stage of growth had passed, became by sub 
. sequent growth Cygnea. The absurdity of regarding species thus — 
made as valid, is self-evident. ine 
The fresh-water mussels of the Colorado desert are associa ed 
with contemporaneous molluscan forms like Physa, Planorbls, 
Tryonia and Amnicola in the Carson City prison-yard, the same : 
form (of mussel) is found with evidences of higher but extinct 
cygnea. . a 
_ The paper presents also reviews past and present geologicalant : 
physico-geographical conditions, and assigns the Carson footprint 
beds to the uppermost tertiary. in 
The general tenor of the paper, which is quite lengthy, oust ; 
Professor Weatherby’s view as to the earliest fresh-water M 
lusca being lacustrine. © 
On THE Eastern Rance or Unio pressus (Lea).— This sf 
was originally described by Dr. Lea, and figured (in Trans? 
Phil. Soc., Vol. 11, 1830, pp. 450~451, plate x1.) under the name 
of Symphynota compressa, from Ohio, and also from Norm 
Kill, near Albany, where it was found by Dr. Eights. It has smi 
been found in the northern canal at Troy, N. Y., by T. H. Aldrich; 
$ 
at the outlet of Owasco lake, by Dr. Jas. Lewis; and ina ma 
