HELTX. 15 



anteriorly ; aperture with thick lip, projecting internally above 

 in two thick, subconfluent tubercles. Diam. 25 mill. 



Arabia Petrsea, Judea. 

 Bourguignat has described a var. ZONATA. 



H. FILIA, Mousson. PL 2, figs. 70, '71. 



Imperforate, rather solid, striulate, shining, white ; whorls 4, 

 a little convex, the last subdepressed, rounded, constricted and 

 deflected in front; aperture with a parietal tubercle at the junc- 

 tion of the upper lip, lip irregular, profoundly sinuous. 



Diam. 17 mill. Palestine. 



Group III. PATULA, Held, 1837. 



Shell umbilicated, discoidal, turbinated or trochiform, rugose 

 or strongly striated, usually horn-colored, frequently strigated, 

 maculated or banded with chestnut ; whorls gradually enlarging, 

 lip of the aperture simple, sharp; jaws smooth or slightly striated, 

 with a more or less marked median projection. There are several 

 hundred species ; distribution universal. The synonymy includes 

 Delomphalus, Agassiz, 1837; Euryomphala, Herm., 1846, and 

 Discus (in part), Ads., 1855. 



The following sections have been proposed : 



Section Discus, Fitzinger, 1833. 



Shell depressed, widely umbilicated, periphery rounded. 

 This is the typical division, of which H. ROTUNDATA, Miill., may 

 be considered an example. The species inhabit Europe, the 

 United States, Polynesia, etc. 



Subsection PUNCTUM, Morse, 1864. 



Shell minute, orbicularly depressed, umbilicus usually moder- 

 ate or narrow, surface costate or strongly striated. Jaw com- 

 posed of distinct quadrate overlapping plates, or imbricately 

 folded. Type H. PYGM^EA, Drap. Europe. 



I place in this group, as synonyms, Patalastra, Pfr.,1878, and 

 Carthsea and Phryxgnathus, Hutton. 



Subsection PLANOGYRA, Morse, 1864. 



Shell minute, perfectly flat above, umbilicus moderate; whorls 

 very convex, the last one sharply ribbed. H. ASTERISCUS, Morse. 

 United States. 



