DENTELLOCARACOLUS. 295 



suddenly descending in front a third or more the total alt. of shell. 

 Aperture oval or horse-shoe-shaped, horizontal ; margins thickened 

 and reflexed, joined by a callus. Type D. damnata A. Brong., pi. 

 71, figs. 53, 54. 



This genus is established for certain heavy, rough sculptured 

 Helices from the N. Italian Eocene, characterized by the extreme 

 obliquity of the aperture, the heavy parietal callus, and the aspect 

 of the West Indian Pleurodonte formosa, or the Canary Island Hemi- 

 cyclas. Some Obba species are also similar. I am totally unable to 

 recognize any affinity between these shells and the Antillean Helices, 

 and regard the superficial resemblance as merely a case of converg- 

 ence of shell characters, meaningless from a phylogenetic stand- 

 point. Whether the group is to be referred to the Epiphallogona 

 or the Belogona is doubtful, and dogmatic assertions are clearly un- 

 called for. 



The species damnata Brong., eoriacea Sandb., amblytropis Sdb., 

 hyperbolica Sdb., antigone Oppenh. and mazzinicola Greg, belong 

 here. 



Section Prothelidomus Oppenheim, 1890. 



Prothelidomus OPPENH., t. c., p. 120. 



Shell imperforate, solid, globose-depressed ; whorls 4J, the last 

 protracted and sometimes carinated toward the aperture. Aperture 

 horizontal, oval or horse-shoe-shaped ; peristome thickened, edent- 

 ulous, the margins joined by a strong parietal callus. Type P. 

 acrochordon Oppenh., pi. 71, figs. 51, 52. 



This group is only feebly distinguished from the preceding, and 

 as with that, I am obliged to discredit entirely the relationships 

 implied by its name. It contains //. acrochordon Oppenh. (radula 

 Sandb. not Pfr.), and H. oppenheimi de Greg. (H. vicentina Op- 

 penh. not Shaur). The sculpture of the former is like that of Pleur- 

 odonte lima, but the second species is smooth. This shows how much 

 dependence is to be placed on a sculpture resemblance, a subject 

 discussed at more length in the introduction to this volume. 



H. declivis Sandb., which Oppenheim places in Eurycratera, may 

 belong near or in this group or in Dentellocaracolus. 



The peculiar minute form described by Stache as Obbinula an- 

 thracophila (Abh. K. K. Geol. Reichsanst. xiii, p. 119) from the 

 Stomatopsis Horizon, " Cretaceo-eoceiie " of Carniola, may prove to 



