of the Maltese Islands, 7 



Our difficulties do not here terminate ; for, if vre open Bronn'a 

 * Index Palieontologicus,* we find T. grandis, Blum., T. gigan- 

 teus, Schluth., A. ampulla and A. micAtc, Brocchi, T. PeJe- 

 Montana, Lk., T. fragilis, Kiju., T. spaadjfloidea. Smith, T. per-, 

 forata, Def., T. variabilis. Sow., T. Souferbftma, Nyst, and T, bi^ 

 sinuata, Lk. (all from the Tertiary formation) given as synoayma 

 of a single species, for which Biumenbach's name " grandit" ia 

 retained. It is quite evident that, if all the shelU above named 

 are not mere modifications of a single very variable species, they 

 are at any rate very nearly related fonns, and have not yet been 

 distinguished in a satisfactory manner. 



M. Meneghini of PLia and Prof. Seqaensa of Messina, who 

 have both bad ample opportunities of studying the shell under 

 description, would i'eel disposed to consider it specifically distinct 

 from T. gr.tndts and 7\ ampul'a, but at the same time arc ready 

 to admit that it is at times difficult to separate certain forms of 

 T. ampulla and T. sinuosa. Brocchi himself describes a variety 

 of T. ampulla in the following words : — " plicis eminentioribus, 

 margine inferiore sinuata,'' which shows that one variety or 

 modification in shape of his T. maipmUm waa, aooording to that 

 naturuli.st, bipltcatecl. I^>th the learned Itahao Profeaaora above 

 named arc, however, uf opinion that T. gram&s and T. empmUm 

 arc more uniformly convex and globose, and that they differ also 

 slightly from T. simtosm in the details of their loop (?). 



It is, however, very possible, and even probable, that T. nmiMg 

 is nothing more than a biplicated variety of T. gramdis or of 71 

 ampulla ; and it was registered under the last-named denomina- 

 tion by the Ute Prof. E. Forbes and by Capt. Spratt in their 

 descriptions of the geology and fossils of Malta. The reason why 

 I have here retained the term 7*. tumota in preference to T. am- 

 pulla is, that, having examined a large number of middle-aged 

 examples from Tuscany &s well as from Malta, I found them all 

 so extremely bipUcated, that they differed in thia reapect ao 

 materially from similar specimens of T. grandis and T. ampmlU 

 I have been able to examine, as to have made me question the 

 propriety of at present classing them all under a single denomi- 

 nation. It will remain also still to be determined whether the 

 parent form may not have existed in the Cretuceous or Jurassic 

 period ; but we may at any rate assert that we are not acquainted 



thrown into fresh oonfiuioD by takiiif; away the term bipUcata (torn the well- 

 known Cretaceous shell and giving it to the equally well-known T. inden- 

 tata, to which Hrocchi's im|H-rfi.ct shell is supivused to belong. Broccbi't 

 name in conuexiun with T. biplicata shouUl therefore in future be com- 



}»letely expunged, and Sowerby** well-known term biplicata be preserved 

 or the Cretaceous sh«U. 



