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PROCEEDINGS OF THE NATIONAL MVSETJM. 



VOL. XXXI. 



hanging, giving rise to channeled sutures. The internal cohimn 

 differs from C. pittlerl in having much more regular lamclhv, which 

 are rarely interrupted. Between these lamclke there appear irregu- 

 larly rounded nodules and elongate tubercles. The base of the 

 pillar is smooth below the twist in each whorl, as in 'piUieri. 



The type has 9,9 whorls and measures: Length, 41.8 mm.; 

 diameter of p(Mudtimate whorl, 14 mm.; diameter of fourth to last 

 whorl, 14.3 mm.; diameter of tirst whorl, T mm. 



PTYCHODONTA, new subgenus. 



Shell with the exterior aspect of Coelocen- 

 trum ss. Internal pillar about one-third the 

 diameter of the inside of the shell, thin, crossed 

 l)y many thin, obsolete, oblique lamelhe. The 

 pillar liears a moderately strong spiral lamella 

 situated a little below the middle in each whorl, 

 from which a series of slender, curved teeth 

 project outward and forward into the cavity. 



Fig. .5.— Interior view of Ccelo- 

 centeum astrophorea 



Fiii. 0.— a, Pillar of the third and fourth 



TO LAST WHORL OF CCELOCENTRUM ASTRO- 

 PHOREA; 6, The pillar of the penultimate 



WHORL OF CCELOCENTRUM ASTROPHOREA. 



In the penultimate whorl and the early whorls these teeth give place 

 to broad, triangular spines, which gained the name astrophorea for 

 the type species. 



CCELOCENTRUM (PTYCHODONTA) ASTROPHOREA Dall. 



There are four specimens and two fragments of this form in the 

 collection. Cat. No. 134690, U.S.N.M., collected l)y E. W. Nelson at 

 Encarnacion, Hidalgo, Mexico. 



Measuremi'nta of Onlocentram {Pli/chodonfa) anfrophorea. 



« Type. 



