340 W. H. HUDLESTON, ESQ., M.A.^ F.E.S., ON THE ORIGIN 



Mdania admirahilis of Lake Tanganyika — at least, I suppose that both 

 of these cuts are intended for the Tanganyika shell, and not for the 

 Jurassic fossil. The likeness is by implication only, for on referring to 

 page 273 for the affinities of Melania admirahilis I find no recognizable 

 account of that species. It is true that on page 269, the author makes a 

 general attack upon the genus Melania ; but this is rather with a view 

 of criticising the suggested relationship of Tyjphohia to Melano'psis. 



The shape and ornamentation of Melania admirahilis (judging from 

 the figures), and Cerithium suhscalariforme are singularly identical. 

 There is some diff'erence in the apertures, for in C. suhscalariforme there 

 is a well-formed anterior spout slightly refiexed. Not having any 

 specimen of M. admirahilis in my possession, I cannot pursue the 

 comparison any further. 



2. Typliohia horei, Smith, with the genus Ptirpiwoidea, Morris and Lycett. 



Mr. Moore in this case does not institute any close comparison, but 

 rather suggests (p. 350) that Typhohia is matched by the Oolitic fossil 

 genus, Purpuroidea, "from which it is difficult, if not impossible, on 

 conchological grounds, to distinguish it." I select Purpnroidea Morrisii, 

 Buvignier, a characteristic Great Oolite fossil, to exemplify the genus. 



Here the ornamentation and general strombiform character of the 

 shell in each case is strikingly apparent. On comparing the apertures 

 we find that, instead of the short notch of Purpuroidea, the inner lip of 

 Typhohia is produced anteally into a narrow and refiexed spout. In 

 other respects both the outer and inner lip in Typhohia and Piirpuroidea 

 greatly resemble each other and equally difi'er from Stromhus. Whilst 

 recognising a considerable degree of homseomorphy between the two 

 shells from Tanganyika and Minchinhampton respectively, a comparison 

 of the shell substance seems to suggest important difi'erences. So far as 

 we are able to judge from the usual calcite replacement of the fossil shell, 

 one would say that Purpuroidea had a thick and heavy shell. On the 

 other hand Typhohia has a very thin and fragile shell, and, despite its 

 identification as a halolimnic shell, has all the appearances of a fresh- 

 water genus — so much so, indeed, that its affinities with Melania have 

 been suspected by some, though this would seem to be negatived by 

 internal characters. As regards the history and distrilDution of 

 Purpuroidea, the genus makes a doubtful appearance in the Inferior 

 Oolite of the east of England ; it is fairly abundant in limited districts 

 of the Great Oolite and is last seen, so far as England is concerned, in 

 the Corallian of Yorkshire. It would seem also to be fairly abundant in 

 the Corallian beds described by Buvignier. It does cot occur on a 

 higher horizon in this part of Europe. 



3. Bathanalia howesi, Smith, loith Amherleya orhignyana, Hudl. 

 Bathanalia is figured on pp. 227 and 348. Of this peculiar genus 

 Moore says (p. 228) that it is an inhabitant of deep water throughout 



