ART. 20 ADDITIONAL MOLLUSKS FROM ECUADOK BARTSCH 13 



summit of the turns there is a smooth area a little wider than the 

 four spiral cords mentioned. The spiral cords, in joining the axial 

 ribs, render these slightly tuberculated. Suture moderately im- 

 , pressed. Peripherj'^ well rounded. Base very long, moderately 

 rounded, marked by the continuation of the axial ribs, which evanesce 

 after passing the middle of the base, and five spiral cords which 

 are of equal spacing but become somewhat enfeebled. On the 

 posterior half of the base, where the axial ribs are present, the spiral 

 and axial sculpture inclose rectangular pits not unlike those of the 

 spire. Aperture very elongate-oval ; outer lip thin, showing the ex- 

 ternal sculpture within ; inner lip very stout, long, reflected over and 

 appressed to the base for almost its entire length, provided with a 

 very strong oblique fold a little anterior to its insertion; parietal 

 wall covered by a moderately thick callus. 



The type (Cat. No. 363088, U.S.N.M.) has lost the nucleus and 

 probably the first one and one-half postnuciear turns. The four and 

 one-half remaining turns measure, length, 2.7 mm. ; diameter, 1 m. 

 Cat. No. 363089, IJ.S.N.M., contains two additional specimens. 



ODOSTOMIA (CHRYSALLIDA) ATA. new species 



Plate 2, fig. 8 



Shell moderately large, very elongate-ovate, bluish-white. Nuclear 

 whorls decollated in the type. Postnuciear whorls slightly rounded 

 jind shouldered at the smnmit, marked by strong almost vertical 

 axial ribs, of which 16 occur upon the first, 18 upon the second to 

 fourth, and 16 upon the last turn. Intercostal spaces about one and 

 one-half times as wide as the ribs, crossed by five spiral cords of 

 which the first is really the thickened summit which occupies the 

 space almost three times the width of the remaining four cords, 

 which are equal. The first of the remaining cords is about one- 

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

 the summit. The space separating this cord from the one at the 

 summit is a little wider than the rest which are also equal. The spaces 

 inclosed between the cord at the sunmiit and the first below it and 

 the ribs are almost squarish pits, while the other spaces between the 

 spiral cords and the axial ribs are rectangular pits having their long- 

 axis parallel with the spiral sculpture. The junction of the axial 

 ribs and spiral cords form slender tubercles, those at the summit 

 being low and rounded, while the other four are elongated with 

 their long axis parallel with the spiral sculpture. The summits of 

 the whorls are shouldered. Suture well impressed but not broadly 

 channeled, marked by the fifth spiral cord. Base rather long, well 

 rounded, marked by six rather strong well rounded spiral cords 

 which are considerablv wider than the spaces that separate them. 



