NO. 1452. NO TES ON P YRA MIDELLID.E—DA LL A XD BA R TSCII. 359 



broader than the keels and crossed by many, very slender raised axial 

 threads. Three keels are present upon the first and second, on the 

 third a fourth keel appears partly at the suture, but the greater part 

 of it is covered up b}' the summit of the succeeding volution. The 

 penultimate whorl has four keels, the posterior one of which marks 

 the sununit and is a little wider than the rest and somewhat flattened. 

 Periphery of the last whorl marked by a sulcus. Base well rounded, 

 attenuated, ornamented like the spaces between the sutures, having six 

 spiral keels. These keels, as well as the sulci, gradually diminish in 

 breadth from the peripher}^ to the umbilical region. Aperture oval, 

 outer lip thin, showing the external sculpture within; columella rather 

 heavy, somewhat curved, backed up by the attenuated base and pro- 

 vided with a strong oblique fold at its insertion; parietal wall covered 

 by a thin callus. 



The type belongs to the Pietel collection and comes from Japan. It 

 has five and one-half post-nuclear whorls and measures: long, 2.6 mm. ; 

 diam., l.H mm. It was labeled Evalea Jmda A, Adams, but is not that 

 species. The U. S. National Museum has two specimens of Odostonita 

 {O(ietta) lli'ida A. Adams, from the author, which are much smaller, 

 more slender, more oval, and less prominently sculptured than the 

 present species. 



ODOSTOMIA (ODETTA) CIRCINATA A. Adams. 



Plate XXIII, tig. 6. 



(hcJIla rircinata A. Adams, Proc. Zool. Soc, 1867, p. 311. 



Shell elongate-oval, subdiaphanous. Nuclear whorls small, almost 

 com]jletely immersed in the first post-nuclear whorl, only the rounded 

 two-thirds of the last volution are visible, and those indicate that the 

 axis of the nuclear turns must be at a right angle to the axis of the 

 later whorls. Post-nuclear whorls moderately well rounded, the last 

 one somewhat inflated, shouldered, marked b}" strong, broadly rounded, 

 subequal and subequally spaced spiral keels, which are separated by 

 deep, rounded sulci, which are about as wide as the keels. The sulci 

 are crossed b}' extremely fine and ver}^ closely spaced axial raised 

 threads which pass up on the sides of the spiral keels, but do not cross 

 their sunmiits. The second and third whorls have three keels between 

 the sutures. On the third the posterior keel at the summit of the 

 whorl, which is a little wider than the other two, shows a spiral stri- 

 ation on its middle. This grows gradually stronger as the shell 

 advances, until on the penultimate whorl it has divided this keel into 

 two, the posterior one of which is a little less developed than the ante- 

 rior one, which resembles the other between the sutures. The summit 

 of the last whorl falls considerably below the peripher}-, showing five 

 spiral keels between the sutures on the penultimate whorl. Periphery 

 J of the last Avhorl sulcate, sulcus like the rest and similarly sculptured. 



