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GASTEROPODA OF THE INFERIOR OOLITE. 



caii be traced are anteriorly bicarinate ; in the next stage a posterior spiral is 

 further developed ; later still there are four spirals, of which the third forms the 

 most salient carina ; the spirals are more or less tuberculate ; in the interspaces 

 subordinate spirals may be detected. 



The ornamentation of the body-whorl is very elaborate. There are five 

 primary spirals, the fourth being the most salient, and constituting with the fifth 

 a double carination. In the posterior spiral the nodules are nearly circular, the 

 other spirals are serrated ; there are about half a dozen deeply-serrated spirals in 

 the base ; the interspaces throughout are cross-hatched with coarse axial lines. 



The aperture is ovate-elongate in the earlier stages, with a certain amount of 

 anterior canaliculation, but becomes more round in the larger shells, as is usually 

 the case with Amberleya. 



Relations and Distribution. — This might almost be called Amb. Meriani, Goldf., 

 var. major. The ornamentation, as shown in the enlargement of that author's 

 figures, greatly resembles the ornaments of Amb. cygnea. But ours is a finer and 

 more eucycloid form, which possesses peculiarities worthy of distinction. It differs 

 still further from d'Orbigny's Turbo Meriani (T. J. ii, pi. cccxxxv, figs. 1 — 5). 



The " Bastard-bed," in which this handsome member of the ornata-grouip 

 occurs, lies at the base of the Lincolnshire Limestone, and just above the Iron- 

 stone at Lincoln. Here Amb. cygnea is fairly plentiful in a rough fawn-coloured 

 matrix along with many other interesting Gasteropoda. 



214. Amberleya goniata, Deslongchamps, 1860. Plate XXII, fig. 6 (juv.). 



1S60. Euctclus goniatus, J. A. Leslongcliamps. Bull. Soc. Linn. Norm., 



vol. v, p. 31, sep. copy, pi. xi, fig. 6. 

 1873. Ambeeleta r goniata, Best., sp. Tawney, Dundry Gasteropoda, p. (20) 



28, pi. ii, fig. 5. 



The type occurs in the Inferior Oolite of Les Moutiers. The specimen figured by 

 Tawney appears correctly identified with Deslongchamps' species, which is probably 

 only a bizarre variety of the one described on the next page. Fig. 6 most likely 

 represents the young stage. This form is found rarely in the Parlcinsoni-zone of 

 Burton Bradstock. It is more markedly angular and more coarsely ribbed than 

 the commoner form next to be described, and has rather a wider spiral angle. All 

 members of the goniata- group have a sharp spire with an obtuse apex (see 

 enlargements of figs. 6 and 11). 



