i6 



12. Dentaliu7n Michelottii Hoernes nov. rec. spec. PI. V, fig. 23, 24. 



1856. Dentalimn Michelottii Hoernes, Foss. Moll. tert. Beck. Wien, p. 654, fig. 84, 85, 86. 

 1897. Dentaliiun Michelottii Hoernes. Sacco, I Moll. d. terr. terz del Piemonte e della Liguria, 

 Parte XXII, p. 96, Tav. YII, figs. 84, 83, 86. 



Stat. 159. o°59'.iS., 1 29° 48'. 8 E. 411 Metres. Coarse sand. 2 Spec. 



Diagnosis. Shell long, attenuated, not much curved, white and shining. Hexagonal 

 at the top, anteriorly smooth and rounded. .Sculpture of 6 sharp ribs vanishing totally before 

 the shell's second half. None or a very weak interstitial thread appear at some distance from 

 the tojj in the interstices. Second half of the shell's surface smooth, very brilliant with faint 

 superficial growth striae, perfectly round in section. Apex entire, hexagonal. Anterior aperture 

 rounded, rather oblique. 

 Length 68 mill.; greatest diameter 3,5 mill. 



Distribution. Tertiary Basin of Vienna, Tertiary Strata of Italy. 



Remarks. Due to the kindness of Prof. Sacco, of sending over from the Torino Museum 

 a specimen of D. Michelottii, I was able to compare the fossil form with the Siboga types. After 

 comparison, little doubt is left, that both forms are identical. Hoernes and Michelotti were the 

 first to distinguish the fossil shell properly. It was known to them from the Basin of Vienna; 

 afterwards many authors have reported it from the tertiary strata of Italy. Sacco describes some 

 specimens from the Tertiary (lower miocene) of Piedmont and Liguria, where it seems to be 

 rather frequent. He distinguishes the following varieties: inter costicellata, rottmdtilina, rotundo- 

 siinplex, costjilatior, costtilatissinia. 



Group of D. katowense. 



Small species, seven-ribbed at apex. 



I. Interstices with fine riblets, length 14 mill. 10 times the diam chevcrti. 



II. Interstices subdivided by secondary riblets and finely longitudinally striated. 



Length 14 mill. 7 times the diam . katowense. 



*I3. Dentaliuin Katoivense Brazier. 



1877. Dentalimn Katowense Brazier, Proc. Linn. Soc. N. S. Wales II, p. 56. 



1897. Dentaliuni Katoivense Brazier. Pilsbry & Sharp, Man. of Conch, vol. XVII, p. 9. 



Diagnosis. Shell white, thin, transparent, slightly arched near the apex; 7-ribbed, 

 from the center to the base 14, those above being most conspicuous; interstices with minute 

 lengthened striae; apex thickened; perforation small, entire; aperture circular. (Brazier). 

 Length 14; diam. of apex i; base 2 mill. 



Distribution. Katow, New Guinea 8 fathoms, sandy mud and coral (Chevert Exp.). 



Remarks. Brazier adds: A white species with 14 ribs on the base, having 7 at the 

 apex more defined. 



