2Y4 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.42. 



ODOSTOMIA (CHRYSALLIDA) HETEROCINCTA, new specieSc 



Plate 36, figs. 4, 4a. 



Shell moderately large, elongate-conic, with decidedly channeled 

 sutures, white. Nuclear whorls at least 2, forming a depressed 

 helicoid spire, which is obliquely, almost one-half immersed in the 

 first of the succeedmg turns. Post-nuclear whorls moderately 

 rounded, marked by strong, decidedly retractive, axial ribs and, on 

 the first four turns, by three spiral cords which equal the ribs in 

 strength; the middle one of these three cords is a little nearer that 

 at thfe summit than to the one. anterior to it. Of the ribs, 16 occur 

 upon all the whorls. The intersections of the ribs and spiral cords 

 form strong, compressed tubercles, the long axes of which coincide 

 with the spiral sculpture. The spaces between the cords and ribs 

 are well rounded, strongly impressed pits. The median cord on the 

 first four whorls is a Uttle stronger than the other two. On the 

 penultimate whorl a slender, spiral cord makes its appearance, be- 

 tween the median and the supraperipheral cprd, which on the last 

 turn, immediately behind the aperture, attains a strength equal to 

 that of the spiral cord at the summit. Entire surface of the spire 

 marked by numerous, very fine, incremental lines. Periphery of the 

 last whorl marked by a deep channel across which the axial ribs 

 extend feebly. Base of the last whorl well rounded, marked by 

 four strong spiral keels, which are subequally spaced and grow some- 

 what weaker successively from the peripheral to the umbilical area. 

 Immediately anterior to the last of these spiral keels there is a single, 

 slender, raised spiral thread. The spaces between the spiral keels 

 are crossed by slender continuations of the axial ribs and very fme 

 hnes of growth. Aperture oval; outer Hp (fractured); inner lip 

 oblique, strong, slightly reflected upon and adnate to the base, pro- 

 vided with a moderately strong fold at its insertion; parietal wall 

 glazed with a thin callus. 



The type, Cat. No. 212033, U.S.N.M., was dredged at United States 

 Bureau of Fisheries station 2932, in 20 fathoms, on sand bottom, 

 bottom temperature 58°, oflF San Diego, CaUfornia. It has 6 post- 

 nuclear whorls and measures: Length, 3.2 mm.; diameter, 1.3 mm. 



The present species is the first one that we have seen from the 

 west coast of America having three nodulose, spiral cords between 

 the sutures. This should be the first species in the key. 



ODOSTOMIA fCHRYSALLIDA) DICELLA, new species. 

 Plate 36, fig. 1. 



Shell small, elongate-ovate, somewhat translucent, bluish-white. 

 Nuclear whorls small, very obliquely immersed in the first of the 

 succeeding turns. Post-nuclear whorls well rounded, marked by four 

 spiral cords between the sutures, the three posterior of which are 



