394 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



vol. 40. 



spiral keels, of which the first below the periphery is much larger than 

 the rest, which are subequal and subequally spaced. Aperture ovate, 

 somewhat effuse anteriorly; posterior angle acute; outer lip thin, 

 showing the external markings within; columella short, very broad 

 at base, oblique, and reflected. 



Doctor Carpenter based his description upon two co-types (Cat. 

 No. 15584, U.S.N.M.) collected at Monterey, California, and Neah 

 Bay, Washington. One of these has ten post-nuclear whorls and 

 measures: Length 10.2 mm., diameter 3 mm. The other has eight 

 post-nuclear whorls and measures: Length 8.8 mm., diameter 2.9 

 mm. Doctor Carpenter's type of B. ( ? var.) esuriens is a young shell 

 in a good state of preservation (Cat. No. 14832, U.S.N.M., fig. 2). 



Bittium attenuatum is a quite variable form, the color ranging from 

 white to chestnut brown at times, variously banded or maculated. 

 The sculpture at times is quite feeble, at others very pronounced. 

 The posterior truncation of the spiral cords and their gentle sloping 

 anteriorly is characteristic of the species. The number of ribs is 

 variable; in some specimens as many as twenty-four occur upon the 

 last turn. There is also an occasional tendency to an intercalation 

 of slender, spiral threads between the prominent keels. 



Specimens examined. 



Catalogue 

 No. 



Locality. 



Number of 

 specimens. 



32200 

 15584 

 23201 

 23301 

 23728 

 32207 

 32224 

 55996 

 55997 

 55998 

 55999 

 50000 

 56844 

 56850 

 56852 

 56001 

 14832 



56677 



56907 



50908a 



158773 



160070d 



160077a 



14849 



153443a 



185363 



195122 



195123 



195124 



109513 



120078 



50665 



160078 



195121 



212023 



Vancouver Island 



Neah Bay and Monterey (cotypes) . 

 Monterey, California 



.do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 



Monterey or Santa Barbara, California (type of B. (? var.) 



esuriens) : 



San Miguel Island, California 



Catalina Island, California 



. . . .do 



.do. 

 .do. 

 .do. 



San Pedro, California 



...do 



...do 



do 



do 



Whites Point, San Pedro, California 



Terminal Island, San Pedro, California... 



San Diego, California 



do 



do 



Foot of Ash Street, San Diego, California. 



FOSSIL. 



Lower San Pedro series, Deadman's Island, California. 



1 

 2 

 6 

 6 

 1 

 7 

 3 

 3 

 4 

 4 

 3 

 2 

 5 

 5 

 5 

 2 



1 

 1 



15 

 3 

 1 

 1 

 2 

 3 

 3 

 1 



13 

 3 

 180 

 1 

 4 

 2 

 4 

 2 



