of the Maltese Islands, 7 
Our difficulties do not here terminate; for, if we open Bronn’s 
‘Index Palontologicus,’ we find T. grandis, Blum., T. gigan- 
teus, Schloth., A. ampulla and A. sinuosa, Brocchi, T. Pede- 
montana, Lik., T. fragilis, Kon., T. spondyloidea, Smith, T. per- 
forata, Det., T. variabilis, Sow., T. Sowerbyana, Nyst, and 7. bi- 
sinuata, Lk. (all from the Tertiary formation) given as synonyms 
of a single species, for which Blumenbach’s name “ grandis”? is 
retained. It is quite evident that, if all the shells above named 
are not mere modifications of a single very variable species, they 
are at any rate very nearly related forms, and have not yet been 
distinguished in a satisfactory manner. 
M. Meneghini of Pisa and Prof. Sequenza of Messina, who 
have both had ample opportunities of studying the shell under 
description, would feel disposed to consider it specifically distinct 
from T. grandis and T. ampul!a, but at the same time are 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 7. ampulla was, according to that 
naturalist, biplicated. Both the learned Italian Professors above 
named are, however, of opinion that 7. grandis and T. ampulla 
are more uniformly convex and globose, and that they differ also 
slightly from 7. sinwosa in the details of their loop (?). 
It is, however, very possibie, and even probable, that 7. sinuosa 
is nothing more than a biplicated variety of 7. grandis or of T. 
ampulla; and it was registered under the last-named denomina- 
tion by the late 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. sénwosa in preference to 7. am- 
pulla is, that, having examined a large number of middle-aged 
examples from Tuscany as well as from Malta, I found them all 
so extremely biplicated, that they differed in this respect so 
materially from similar specimens of 7. grandis and T. ampulla 
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 Cretaceous or Jurassic 
period ; but we may at any rate assert that we are not acquainted 
thrown into fresh confusion by taking away the term beplicata from the well- 
known Cretaceous shell and giving it to the equally well-known T. inden- 
tata, to which Brocchi’s imperfect shell is supposed to belong. Brocchi’s 
name in connexion with T. biplicata should therefore in future be com- 
pletely expunged, and Sowerby’s well-known term biplicata be preserved 
for the Cretaceous shell. 
