650 PROCEEDINGS OP THE NATIONAL MUSEUM. vol.52. 



wide as the ribs, crossed by eleven incised spiral lines between the 

 sutures, of these the fifth is the widest, being fully twice as wide as 

 the third and sixth, which are of equal strength, the remaining are 

 much more slender and also of equal strength. In spacing the first 

 is about as far anterior to the summit as the second is distant from 

 the third, or the fourth from the fifth, or the fifth from the sixth, 

 while the space between the first and second, and those between the 

 sixth and the seventh, are about equal, the spiral markings pass up 

 on the sides of the ribs and the stronger ones tend to cross their 

 summit. Suture moderately constricted. Periphery of the last 

 whorl decidedly angulated. Base short, slightly rounded, marked 

 by the very feeble continuations of the axial ribs, which become 

 evanescent before reaching the middle of the whorls, and thirteen in- 

 cised spiral lines, which are about equally spaced, the first one below 

 the periphery being a little nearer to its neighbor than the spacing be- 

 tween the rest, the space between the seventh line of the spire and the 

 first incised spiral basal line is a broad, smooth band. Aperture sub- 

 quadrate, posterior angle obtuse; outer lip thin, showing the ex- 

 ternal sculpture within; inner lip almost straight and slightly revo- 

 lute ; parietal wall covered with a thin callus. 



The type. Cat. No. 250625, U.S.N.M., was collected by Mr. Gripp 

 on kelp, in 15 fathoms, off San Diego Bay. It has eight and one- 

 half postnuclear whorls, and measures — length, 6.1 mm. ; diameter 

 1.9 mm. 



TURBONILLA (PYRGISCUS) ISTA. new species. 



Plate 42, fig. 6. 



Shell rather large, elongate conic, light brown. Early whorls light 

 yellow. Nuclear whorls decollated. Postnuclear whorls appressed 

 at the summit, which is slightly excurved, marked by rather poorly 

 developed, almost vertical, axial ribs, which become obsolete on the 

 later whorls. Of these ribs, 18 occur upon the second and third, 20 

 upon the fourth, 22 upon the fifth, 24 upon the sixth, 26 upon the 

 seventh, 28 upon the eighth, 30 upon the ninth, and 32 upon the 

 tenth, while upon the penultimate they are too irregular to be 

 counted. Intercostal spaces very feebly impressed, about as wide as 

 the ribs. The spiral sculpture consists of strong and weak incised 

 lines, the strong lines pass strongly upon the sides of the ribs and 

 even cross the summit; the first of these strong lines is about one- 

 fifth of the distance between the summit and the suture anterior to 

 the summit, while the spaces between the first and second, the third 

 and fourth, the fourth and fifth, and the fifth and sixth are almost 

 equal and about two-thirds as wide as that between the second and 

 third ; of the finely incised spiral lines eight occur between the sum- 

 mit and the first strong line and three between the first and second, 



