674 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



BITTIUM SANTAMARIENSIS. new species. 



Plate 47, fig. 3. 



Shell elongate conic, pale brown. Nuclear whorls decollated. Post- 

 nuclear whorls well rounded, narrowly tabulatedly shouldered at 

 the summit, becoming decidedly contracted between the fourth spiral 

 cord and the suture, marked by narrow, well-rounded, almost vertical 

 axial ribs of which 14 occur upon the first and second, 16 upon the 

 third and fourth, 18 upon the fifth, and 20 upon the last turn. In 

 addition to the axial sculpture, the whorls are marked by four strong 

 spiral cords which are equal and equally spaced, the space between 

 them being as wide as the cords. The first of these cords is at the 

 summit. The junction of these cords and the axial ribs form elon- 

 gated, well-rounded tubercles, while the spaces between them form 

 rectangular pits, the long axis of which coincides with the spiral 

 sculpture. On the last whorl a slender spiral thread is present in 

 each groove between the raised keels. Periphery marked by a rather 

 strong spiral cord. The space between this and the fourth cord on 

 the spire bears a slender spiral thread. Base moderately long, con- 

 cave, marked by 8 slender spiral threads which are not quite as broad 

 as the spaces that separate them. Aperture broadly oval, moderately 

 channeled anteriorly ; posterior angle obtuse ; outer lip thin, rendered 

 sinuous by the spiral sculpture ; inner lip oblique, somewhat concave, 

 reflected over and appressed to the base ; parietal wall covered by a 

 thin callus. 



The type. Cat. No. 268623, U.S.N.M., was collected in shallow 

 water in Santa Maria Bay, Lower California. It has 6^ postnuclear 

 whorls and measures — length, 4.9 m. ; diameter, 2 mm. 



BITTIUM SANJUANENSIS. new species. 



Plate 47, fig. 4. 



Shell verv large, rather thin, bluish white. Nuclear whorls decol- 

 lated. Postnuclear whorls almost appressed at the summit, well 

 rounded, decidedly contracted immediately posterior to the suture, 

 marked by strong, broad, heavy, slightly protractive axial ribs which 

 become enfeebled toward the summit and slightly widened there. 

 Of these ribs, 12 occur upon the second and third, 14 upon the fourth 

 and fifth, and 16 upon the last whorl. Intercostal spaces not quite 

 as broad as the ribs. The spiral sculpture consists of five cords, of 

 which the first, which is at the summit, is very slender. The two 

 succeeding this are successively a trifle stronger, while the fourth 

 and fifth are very strong, the last being the heaviest of all. The 

 junction of the axial ribs and the spiral cords form well-rounded, 

 elongated nodules which have their long axis parallel with the spiral 



