CLASS SCAPHOPODA 
13 
faces is parted by a median riblet; and a little farther on a tertiary series 
of riblets, one on each of the intervals except the two bounding the keel 
of the convex side, in which intervals small riblets develop later. At the 
middle of the shell's length the section is circular and the 28-30 riblets 
nearly equal in size; a few threads are intercalated toward the aperture, 
where the riblets are slightly unequal, low, narrow and close. Aperture 
circular, slightly oblique. Anal orifice circular, with a slightly raised rim; 
placed in the middle of the square apex. Length, 14.1; diameter at aper¬ 
ture, 1.8; at apex, 1.2 mm. (Pilsbry.) 
Provisional name only; no description. (Pilsbry.) 
Type in United States National Museum, No. 46204. Type locality, 
Los Animas Bay, Lower California. 
Range. Los Animas Bay, Gulf of California. 
Dentalium vallicolens Raymond, 1904 
Plate 1, fig. 2 
Nautilus , 17:123. 
Adult shell large, rather slender, moderately curved posteriorly, the 
latter half nearly straight; cream-white, often yellowish toward the mouth, 
shining where not eroded, earlier portion usually dull and chalky because 
of erosion; growth-lines fine, irregular, distinct, rarely an encircling groove 
due to repaired fracture; at the apex there are longitudinal, low, rounded, 
inconspicuous threads, of which seven or eight are more prominent and 
three to six in each interspace are less prominent; these die out, and fine, 
superficial striae appear, visible under the glass, and continued to the 
mouth of the shell, seven or eight per millimeter of circumference; aper¬ 
ture simple, circular, mouth slightly oblique. Length, 64.5; diameter of 
aperture, 5.3; of apex, 1.5; at middle, 4.6; height of arch from chord, 
2.5 mm. (Raymond.) 
Type in University of California Collection. Type locality, Station 12, 
submerged valley off Redondo, Santa Monica Bay, in 145 fathoms. 
Range. Straits of Juan de Fuca to Gulf of California. 
Dentalium pretiosum Sowerby, 1860 
Plate 1, fig. 10 
Sowerby, Thesaurus Conchyliorum, 95; PI. 225, fig. 57. 
Testa D. entali simillima, sed angustiore, versus apicem haud tantum 
arcuata. 
Less curved and tapering near the apex than D. entali , and altogether 
more cylindrical. (Sowerby.) 
