350 PROCEEDINGS^ OF THE XATIOXAL MUSEUM. v<.i.. xxx. 



ODOSTOMIA (CHRYSALLIDA) DUX, new species, 

 riute XVII, %. 4. 



Shell ovate-conic. wh[U\ Nuclear whorls moderately laroe, obliiiuel}' 

 deeply immersed in the tir.st post-nuclear whorl, the peripheral portion 

 onlv of the last volution projects above the edge. Post-miclear whorls 

 luoderatelv rounded, strongly crenulately shouldered, marked between 

 the sutures by four spiral keels, the posterior two of which are a little 

 more closcdy spaced than the rest and twenty axial ribs which do not 

 extend entirely across the whorl but terminate at the sulcus which 

 separates the third from the fourth keel. Each jmiction of an axial 

 ril) and a spiral keel is marked })y a tubercle; the tubercles of the 

 first and second keel belonging to the same axial rib are somewhat 

 fused, there being a less prominent constriction between them than 

 between the second and third, the complete effect l)eing that of an 

 exclamation point. The fourth spiral keel is strong and rounded and 

 decidedly elevated, a ver}' slender extension of the axial rib reaches 

 across the deep spiral sulcus, which like the sulci of the base is crossed 

 by tine, subequally spaced, raised axial threads. Base moderately well 

 rounded, attenuated, ornamented with five subequal and subequally 

 spaced, somewhat flattened, spiral keels. Aperture rather large, sub- 

 oval, effuse at the junction of the outer lip and the columella; posterior 

 angle acute, outer lip wavy, thin, showing the external sculpture within; 

 columella strong, curved, reenforced l)y the attenuated base, provided 

 with a strong fold at its insertion; pari(>tal wall covered by a thin 

 callus. 



The type has four post-nuclear whorls, and measures: long. l.Smm.; 

 diam. 1 nun. It is from flapan and belongs to the Pa'tel collection. 



Of the twenty-eight species descril)ed as ChrysalUdd by A. Adams, 

 we have been able to refer onl}" one positively to this group, namely 

 C. jjlicata. 



ODOSTOMIA (^PYRGULINA) DENSECOSTATA Garrett. 

 Plate XVIII, li>r. 4. 



Shell elongate-ovate, very thin, subdiaphanous, milk-white, shining. 

 Nuclear whorls almost completely obli([uely immersed in the first post- 

 midear whorl. Post-nuclear whorls rounded, rather inflated, moder- 

 ately shouldered, and marked by many well-developed, regular, rounded, 

 tcnvard the aperture slanting axial ribs, of which twenty occur upon 

 the second, twenty-four upon the fifth, and thirty upon the penulti- 

 mate whorl. These ribs are somewhat thickened at their posterior 

 extremity and give the sunnnits of the whorls a beaded ai)pearance. 

 Inteicostal spaces a little widei' than the ribs, crossed by many incised 

 spiial lines, which are al>out as wide as the raised spaces between them. 

 These incised spiral lines are a little less strongly developed on the 



