44 LAURIA. 



and short radial laminae at intervals within the basal wall. 

 Embryonic shell usually very finely striate spirally. Type L. 

 cylindracea. 



Distribution : Palamrctic and Ethiopian regions. 



Orcula resembles this genus by having spiral lamellae in the 

 young, but it differs by lacking radial basal lamina?. In the 

 adult stage the angular lamella of Orcula, when present, is 

 tubercular, not lamellar and entering, as in Lauria. 



Lauria comprises two subordinate groups, rather distinct in 

 the apertural teeth, but even more by the reproduction, Lauria 

 proper being viviparous, while the subgenus Leiostyla is ovi- 

 parous. Perhaps these groups should be ranked as distinct 

 genera ; but they are identical in the peculiar armature of the 

 young shells. 



Tertiary Species of Lauria. 



No species of the typical group of Lauria are as yet known 

 from the Tertiary. It is doubtless a derivative of the more 

 fully toothed group Leiostyla, and probably an old branch 

 which may turn up in the Eocene. Its discontinuous, far- 

 flung distribution certainly denotes a considerable antiquity. 

 Probably we will eventually learn that Lauria (Leiostyla) 

 was present in the Paleocene ; the Neocene and Recent species 

 are to be viewed as scattered survivors of an old genus. The 

 extravagant development of teeth and apertural calluses, seen 

 in many species, is an expression of racial old age. 



The following list, contributed by Dr. W. Wenz, of the 

 Senckenbergische Museum, Frankfurt, contains only species 

 of Leiostyla : 



Lauria priscilla (Paladilhe). Vertigo priscilla Paladilhe, 

 Rev. Sci. Nat., ii, 1873, p. 53, pi. 2, figs. 22-24. — Vertigo 

 (Ptychalcra) priscilla, this work, vol. xxv, p. 220. Middle 

 Pliocene, Plaisancien : Celleneuve near Montpellier, France. 



Lauria austriaca "Wenz. Senckbergiana, iii, 1921, p. 28, 

 fig. 2. Lower Pliocene, Pontien : Congeria beds, Leobersdorf , 

 Lower Austria. 



Lauria gottschicki Wenz. Archiv fur Molluskenk., 1922, 

 p. 107, figs. Upper Miocene, Sarmatien : Steinheim am Al- 

 buch, Wiirttemberg. 



