514 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxm. 



The following 6 of the 41 subg-enera and sections of Odostomia are 

 represented in the present faunal area: C/irj/srdlida, Ividia, lolaea^ 

 Mene^tho^ Evalea^ and Am aura. 



KEY To SUBGENERA OK ODOSTOMIA. 



Sculpture nodulose Chrysallida, p. 514. 



Sculjiture consisting of axial and spiral lamelhe Ividia, p. 517. 



Sculpture consisting of spiral liratious and slender axial threads in the depressed 

 spaces: 



Shell umbilicated Ijlaea, p. 518. 



Shell not umlnlicated Meneahn, p. 520. 



Sculpture consistiug of spiral striation only: 



Shell very large .1 umani, p. 528. 



Shell small. Evalea, p. 522. 



Subgenus CHRYSALLIDA Carpenter. 



Chrymllida Carpenter, Cat. Maz. Shells, 1857, ]). 41H. — Noemia De Folin, Fonds 

 de la Mer, 1873, p. 314, not Noemia Pasco, 1S57. — Noemiamni De I'olin, 

 Zool. Rec, 1885, p. 94 (Mollusca). 



Odostoniias having strong axial ribs crossed b}^ equally strong 

 spiral keels between the sutures, the intersection of these two ele- 

 ments forming nodules. The axial ribs pass onl}^ faintl}" over the 

 base, while the spiral sculpture remains quite prominent. 



Type. — ChrysaUida, coniiininls Carpenter. 



KEY TO species OF CHRYSALLIDA. 



Spiral keels between the sutures 4. 

 Sutures deeply channelled. 



Base with 7 narrow and slender spiral keels - astricfa. 



Base with 8 hroad and rounded spiral keels cooperi. 



Sutures not channelled moniereyensis. 



Spiral keels between the sutures on the last whorl more than 5 oregonensis. 



ODOSTOMIA rCHRYSALLIDA) COOPERI, new species. 

 Plate XL VI, lig. 7. 



Shell oroadly conic, white. Nuclear whorls smooth, largel}^ 

 obliquely immersed in the tirst of the succeeding turns above which 

 only about half of the last turn projects. Postnuclear whorl mod- 

 erately rounded, slopingly >houldered at the summit, the shoulder 

 bearing the first of the four stronger tuberculate spiral ridges. The 

 connections which join the tubercles in th(^ spiral series are a little 

 more strongly developed than those which link them vertically, the 

 spaces inclosed ))etween them being deep squarish pits. The tubercles 

 are very prominent and rounded, there are about 16 upon the second, 

 20 upon the third, and 26 upon the penultimate turn. The axial 

 series slants retractively from the posterior suture. Sutures deep and 

 broad, considerably wider than the spaces between the keels. Periph- 

 ery of the last whorl deeply channelled, the channel marked by a 



