8 PEOCEEDiNGS OF THE NATIONAL MUSEUM. vol. G6. 



The type, Cat. No. 359763, U. S. N. M., has 61/3 postnuclear whorls 

 and measures : Length, 3.1 mm. ; diameter, 1.2 mm. 



The present species is related to Odostomki {Chrysallida) excelsa 

 Dall and Bartsch from Panama, but differs from it in having 5 in- 

 stead of 8 much stronger spiral cords on the base. 



ODOSTOMIA (CHRYSALLIDA) MELITTA. new species. 



Plate 2, fig. 2. 



Shell elongate-conic, bluish white, semitranslucent. Nuclear 

 whorls decollated. Postnuclear whorls narrowly, tabulatedly shoul- 

 dered at the summit, flattened in the middle, marked by very strong, 

 slightly protractively slanting axial ribs, of which 16 occur upon the 

 first of the remaining turns, 18 upon the second, third, and fourth, 

 and 20 upon the last. These ribs are almost as wide as the spaces 

 that separate them. The spiral sculpture consists of 4 strong spiral 

 cords which do not quite equal the ribs in strength. The first of 

 these is at the summit, while the other three divide the spaces between 

 the summit and the suture into three equal areas. The junction of 

 the axial ribs and spiral cords forms low rounded tubercles, while 

 the spaces between them enclose rounded pits. Beginning with the 

 antipenultimate turn, the peripheral cord shows at the suture, and 

 on the last turn it is completely free therein. This cord is a little 

 less strong than those on the spire. Base rather long, marked by 7 

 strong spiral cords, those near the columella being a little less devel- 

 oped than the rest. The latter equal the peripheral cord in strength. 

 The spaces between the cords equal the cords and are crossed by fine 

 axial riblets. Aperture oval; posterior angle obtuse; outer lip thin, 

 showing the external sculpture within ; inner lip very stout, reflected 

 over and appressed to the base, and provided with a very strong, 

 almost lamellar oblique fold a little anterior to its insertion; parietal 

 wall covered by a thick callus. 



The type, Cat. No. 359764, United States National Museum, has 6 

 whorls remaining and measures : Length, 4.2 mm. ; diameter, 1.4 mm. 



This also belongs to the group of Odostorma {Chrysallida) excelsa 

 Dall and Bartsch, but differs from it by its elongate-conic form 

 {excelsa is elongate-ovate) and by its much larger size. 



MELANELLA (MELANELLA) OLSSONI, new species. 



Plate 2, fig. 4. 



Shell regularly elongate-conic, bluish white, semitranslucent. 

 Nuclear whorls decollated. Postnuclear whorls almost flattened, 

 giving to the spire an almost straight outline, appressed at the sum- 

 mit. The basal portion of the preceding whorl shines through the 

 substance of the succeeding turn at its summit, and gives this the 

 appearance of having a double suture. Periphery strongly rounded. 



