C-iKCILIOIDKS. O 



valid form is undoubtedly Csecilioides, in reference to the blind- 

 ness of these tiny subterranean snails. Aciculina of Wester- 

 lund is an absolute synonym of Cxcifioides, having for type the 

 same species, C. acicula. 



Csecilioides occurs in typical species in the Miocene and Plio- 

 cene, the following species being known. All were described 

 under the name Csecilianella. 



Csecilianella grateloupi Bgt. Rev. et Mag. de Zool. 1856, p. 

 431, based upon Bulimus acicula Grateloup, Actes Soc. Linn. 

 Bord. x, 1838, p. 31, pi. 4, f. 23, 24. St. Paul near Dax. 



Cisecilianella aciculella Sandberger, Land und Siisswasser Conch, 

 der Vorwelt, p. 595, pi. 29, f. 15. Upper Miocene, Morsingen. 



Csecilianella polonica Lomnicki, Verh. k. k. Geol. Reichsanst. 

 Wien, 1885, p. 422. Wycolki. 



C. acicula and C. a. irregidaris Sacco have been found in the 

 Pliocene, Villafranchian stage, at Fossano (see Sacco, I Mol- 

 luschi dei terreni Terziarii del Piemonte e della Liguria, pt. 22, 

 1897, p. 76). 



0. a. irregidaris Sacco 1885 (t. c., pi. 6, f. 26) is a form with 

 very rapidly descending last whorl, requiring comparison with 

 recent forms. 



Sections of Csecilioides. 



a. Columella distinctly truncate at the base; spire slender. 

 Chiefly Palaaarctic species. 



b. Columella and parietal wall without conspicuous cal- 

 lus, a low parietal nodule sometimes developed. 



Section Csecilioides, species 1 to 5, 9 to 36. 

 6 1 . Columella with one or two nodules below the middle. 



Section Terebrella, species 7, 8. 



a 1 . Columella varying from truncate to indistinctly subtruncate 

 at base; spire thick, short; shell very small. Tropical 

 America. Section Csecilianopsis, species 37 to 39. 



a*. Columella not truncate or very indistinctly so. 



b. Columella simple, not conspicuously calloused. Trop- 

 ical in both hemispheres. 



Section Geostilbia, species 40 to 47. 

 b\ Columella strongly sigmoid, not truncate at base; a 



