142 EOCENE MOLLUSCA. 



angustd • labro suh-marginato, intus crenulato, postice dilatato ; columella recta, quinquies 



plica id. 



Shell oblong, ovate, with a very short obtuse spire, formed of but few whorls, the 



sutures of which are barely separated from each other ; the body-whorl, which of 

 itself forms almost the entire shell, is widely but not deeply notched in front. The mouth 

 is long, narrow, and curved at the posterior extremity ; the columella straight and, 

 generally, furnished with five folds, occasionally with six or even more; the an- 

 terior folds are larger and more oblique than the others, which decrease in size as 

 they ascend the columella. The outer lip is curved, expanding near the suture into a 

 rounded wing-shaped projection ; it is finely crenulated within, slightly thickened, and 

 presents a narrow raised border running along the outer margin. 



Some confusion appears to exist between the present species and a living species 

 common in the Mediterranean (M. miliacea), placed by Lamarck in his genus Volvaria. 

 This latter species is mentioned by Dujardin as occurring in the miocene formation in 

 the neighbourhood of Tours ; and Philippi and Sismonda have also recorded it as found 

 in the upper miocene of Piedmont. Dujardin's shell, however, appears to be distinct, 

 and the identification of the last is very questionable. The same species is also 

 cited by Grateloup, although with a query, as identical with the present species, to 

 which he has referred some shells from the miocene beds of Bourdeaux and Dax ; but 

 which, as well as certain shells from the synchronous beds of Turin, described by 

 Michelotti as M. ovulata, belong to a different species to which D'Orbigny has given the 

 name M. sub-ovulata. On the other hand, aMarginella from the miocene beds near Vienna, 

 formerly considered to belong to the present species, has been regarded by Homes as 

 identical with M. miliacea, and Philippi has also recorded a shell from Westeregeln, as 

 belonging to the recent species. Dr. Beyrich, however, has pointed out with 

 much precision, the specific differences between the M. miliacea and M. ovulata, and 

 he seems to think that the shells mentioned by Homes and by Philippi, belong in fact, 

 to the present species, which, apparently, is confined to the older tertiary formations ; 

 while, as yet, there is no ground for considering that M. miliacea occurs in any formation 

 older than the upper miocene, if it occur even in that. 



Whether or not the German shells are referable to the present species, is a doubt- 

 ful question. The figure given by Dr. Beyrich does not agree with the French shells ; 

 the spire is more produced ; the aperture, consequently, is proportionally shorter, and 

 it is wider in front ; the outer lip, apparently, is without the wing-shaped projection so 

 characteristic of the true M. ovulata; and the folds on the columella are more distant 

 and more oblique. Bronn's shell, so far as an opinion can be formed from the some- 

 what coarse and indistinct figure given by him, appears to agree much better. 



The specimen figured is, I believe, unique, and although not in a very good state 

 of preservation, is sufficiently so for determining the identity. 



Size. — The French specimens of this species vary considerably in size, some ex- 



