846 W. H. HUDLESTON, ESQ.^ M.A., P.R.S., ON THE ORIGIN 



Out of about thirty genera of oasteropods quoted in Dr. 

 Glangeaud's list from the Lower Oolites of the south-west of 

 France the genus Purpurina does not appear at all, whilst the 

 genus Amherlcya is restricted to a single unnamed species. On 

 the other hand the genus Purpuroidca is recognised.* Going 

 further south again, we look to Choffat for information as to 

 the Jurassic faunas of the Iberian peninsula. Hitherto, I have 

 been unable to come across any systematic list of the gasteropod 

 fauna of the Jurassic beds, though I note in the Faunc 

 Gretacique du Portugal,] a species of Purpuroidca described by 

 that author. There are, however, throughout Choffat's numerous 

 publications many lists of Jurassic fossils, yet I can find nothing 

 which might lead one to suppose that the peculiar Anglo- 

 Norman facies of Inferior Oolite gasteropods can be traced in 

 the peninsula. 



There is one very rich gasteropod fauna of Lias-Oolite age in 

 Sicily which inspired the famous monograph of Gennnellaro : 

 " Sui fossili del calcare cristallino della Montagna del Casale e 

 di Bellampo, nella provincia di Palermo." The gasteropod 

 facies of these beds possesses some forms which appear 

 specifically identical with those of the Anglo-Norman Inferior 

 Oolite. However, there is no Purpurina and only one species 

 of Ambcrhya. 



On a higher Jurassic horizon in the same island, we recognise 

 an Amhcrleya-like form in Eiicychis alptinus. On the whole, 

 however, there is nothing in this assemblage which would help 

 us to connect this gasteropod fauna specially with the lialo- 

 limnic gasteropods of Tanganyika. 



The above enumerations may be regarded in the light of a- 

 search after the stepping stones between the Anglo-Norman 

 basin and Lake Tanganyika ; and if there has ever existed, 

 either in Jurassic, Cretaceous, or Tertiary times, any such 

 connection, direct or second hand, between the region in which 

 Lake Tanganyika is situated and the sea, as is claimed by 

 Mr. Moore, such connection has most probably been from the 

 northwards and ultimately by way of the Congo basin. At any 

 rate the physical configuration of Africa seems to point in this 

 diiection ; and since this is the case, any discovery of Jurassic 

 faunas, such as those of Madagascar, though very interesting in 

 themselves, and in reality much nearer Tanganyika, is of less 



* Bulletin des services de la Carte Ge'ologiqiie de France (No. 50) 

 vol. viii. (1896-7) p. 118. 



t Vol. i (1886), p. 6, Plate I, fig. 1. 



