1918.] N. Annandale : Molluscs of tlie hile Lake. 167 



in Yunnan, is of the opinion that environment and shell-type are corre- 

 lated in a general way, but no precise information is available to him. 



The case of the Austrian Viviparidae is an even more remarkable 

 one and perhaps in some points more closely parallel to that of the Shan 

 Taiae. Neumayr and Paul^ have discussed it in considerable detail, 

 both from a palaeontological and from a strictly geological point of view, 

 in their treatise on the Congeria and Paludina Beds of Slavonia, They 

 recognize no less than thirty-nine species, which Neumayr assigns to 

 the subgenus Tulotoma of the genus Vivipara. The shells of the differ- 

 ent species vary greatly in both shape and sculpture and provide a com- 

 plete transition from normal smooth forms to forms in which the sculp- 

 ture approaches that of the more highly specialized varieties or species 

 of Margarya and Tata and agrees very closely with that of the North 

 American living genus or subgenus Tulotoma, but apparently there is 

 no excessive individual variation within the limits of each species. All 

 these forms come from Tertiary deposits and have long been extinct, 

 but the racial variation was progressive in time as well as in structure 

 and the smooth shells are older than the highly sculptured ones. About 

 these Viviparidae Neumayr [op. cit.) writes as follows : — 



" Wie mein Freund Paul im geologischen Theile nachgewiesen hat, sind in den von 

 uns untersuchten Gegenden von Westslavonien die glatten Viviparen mit ausserst ge- 

 ringer Ausnahine auf die unteren, die mit ausgesprochenen Kielen und Knoten verseh- 

 eiien Formen vollstandig auf die mittleren und oberen Paludinenschichten beschiankt. 

 In der mittleren und obeien Abtheilung konnten zahlreiclie Horizonte unterschieden 

 und auf giossere Erstreckung nachgewiesen werden und in Folge dessen konnten die 

 I'em morphologisch aufgestellten Formenreihen der gekielten und geknoteten Vivijparen 

 sofort der geologischen Controle unterworfen werden. Fiir die unteren Paludinen- 

 schichten konnte eine Gliederung noch nicht durchgefiihrt werden, und es fehlt daher 

 fiir die glatten, wie fiir die nicht von uns selbst gesammelten Formen der Kachweis fiir 

 die Concordanz der chronologischen und morphologischen Reihe." 



It is of course impossible to say precisely in what environment the 

 different species flourished, but it is clear from Paul's sections in the geo» 

 logical part of the treatise on these Slavonian beds, that the molluscs 

 all lived in a country similar in some respects to the Shan Plateau and 

 that some of them were certainly lacustrine. Bourguignat^ says of 

 part of the country in which they were probably evolved : — 



" II a du y avoir, a cette epoque reculee, dans cette partie de la vallee de la Cettina, 

 une vaste depression remplie d'eau salee, qui, peu a peu, par des causes (jui me sont in- 

 connues, sont devenues saumatres, pour finir par etre entierement douces." 



The interest of these two cases so far as our present purpose is con- 

 cerned lies in the fact that they prove that Vivipara, from which Mar- 

 garya and Tulotoma are certainly derived, has, in widely separated 

 districts, and in peculiar circumstances, developed a similar tendency 

 to become extremely plastic and to elaborate the sculpture of its shell 

 in spiral series of nodules. What the circumstances probably were 

 will be considered later. A few other, less striking perhaps but none the 

 less interesting instances of the same kind may be cited more briefly. 



1 Ahh. K. K. Geol. Rekhsanstalt, VII, pp. 1-105, pis. iv-vi (1875). See also Penecke 

 on the Slavonian Paludina Beds in Mojsisovics and Neumayr, Beitr. Falaeontologie Ost.- 

 Ungarns, IV, pp. 15-44, pi. ix (6) (1886). I have to thank Mr. G. de P. Cotter of the 

 Geological Survey of India for these references. 



? fJt. Fo.i.nles tert. ^ '^ua4ern, de. la Valine de la Cettina, p. 2 (Saint-Germain : 1880). 



