AN ANNOTATED LIST OF THE SHELLS OF SAN PEDRO BAY AND 
VICINITY. 
BY 
Mrs. M. Burron WILLIAMSON. 
WITH A DESCRIPTION OF TWO NEW SPECIES BY W. H. DALL. 
(With Plates x1x-x x1. ) 
IT have often thought if the fauna and flora of every inhabited county 
in the United States were studied and reported by careful, conscien- 
tious lovers of nature, the contributions to the natural history of our 
country would be of no small value, not only as a record of the riches 
of nature but, at a future time, as a history of the life that at a certain 
period was identified with a particular locality. For there is nothing 
permanent in nature. -Her activity begets change, and change daily 
makes history. 
With these thoughts in my mind I have undertaken to give a list 
of the marine shell fauna of Los Angeles County found, for the most 
part, within a period of two years. I am indebted to Mrs. L. H. Trow- 
bridge and Miss I. M. Shepard for lists of shells found by them. Some 
of their shells have been identified, through me, by Dr. J. G. Cooper, 
but the greater part, especially the rarer forms, have been determined 
at the Smithsonian Institution, Washington, D.C. Miss 8S. P. Monks, 
teacher of drawing and zoology in the State normal school, in Los An- 
geles, has kindly allowed me to examine the shells found by her as 
well as those in the museum of the normal school. 
There are still some shells that have not been identified. 
The Nudibranchiata are not included in this list. Doris and Wolis 
have been found in San Pedro Bay and at Catalina Island, but not 
specifically determined. 
INTRODUCTORY. 
The coast of Los Angeles County is diversified by two large bays, 
Santa Monica and San Pedro, with their long sandy beaches sepa- 
rated by high, rocky cliffs. On the northwestern coast of the county 
the Sierra de Santa Monica range of mountains rises abruptly from the 
ocean. The extreme western point in this range is known as Point 
Dume, noted for its diatomaceous earth. Running back from this 
point the coast cunves in until it reaches the sandy beach of Santa 
Monica Bay. In this bay Tivela crassatelloides and Tapes staminea 
179 
Proceeding National Museum, Vol. XV—No. 898. 
Is . 
