AMBERLEYA. 285 
215. AmBERLEYA ORBIGNYANA, Sp. nov. Plate XXII, figs. 7, 8. 
PURPURINA ORNATA, d’Orbigny. Terr. Jur., vol. ii, pl. ecexxx, figs. 4, 5. 
Bibliography, §c.—There is no reference to Purpurina ornata in the text of the 
‘Terrains Jurassiques,’ though we gather from the explanation to the plate that 
it is a fossil of the Inferior Oolite. Purpurina ornata is evidently an Amberleya 
(Eucyclus), and we at once recognise the form as common and characteristic of the 
Parkinsoni-zone of Dorset. The specific name ‘ ornata’”’ being preoccupied, it 
becomes necessary to bestow on this fossil a fresh appellation. 
Description : 
Length of well-grown specimens ; . 3d9—45 mm. 
Length of body-whorl to total height . = 50: 100: 
Spiral angle : : < AS 
Shell eucycloid, turrited. Whorls nine or ten, angular, and sloping flatly 
towards the dominating keel. The whorls of the spire are biangulated anteriorly ; 
a faintly nodular spiral is developed close to the upper suture, then ensues the 
flat sloping area, marked by extremely fine strive rather oblique to the axis ; the 
two principal keels or spirals are quite low down, the upper one having large 
tubercles, wide apart and spirally extended; in the lower keel the ornaments are 
usually less conspicuous. 
The body-whorl is large, very angular, with the great keel strongly tuber- 
culated ; there are five spirals in the base, these being slightly tuberculated. The 
aperture is ovate-elongate, with a straight columellar lip much produced anteriorly, 
as in Purpurina. This is the stage in which the shells are usually found. Larger 
specimens have the aperture more circular. 
Relations and Distribution—This may be regarded as the average form of 
the goniata-group. It occurs throughout the Parkinsoni-zone, principally in 
South Dorset, being especially abundant at Burton Bradstock, Loders, &e. It 
also occurs in the upper part of the Humphriesianus-zone at Louse Hill, and in the 
Parkinsoni-zone at Grove, &c. Casts of this form are found in the Parkinsoni- 
or Martinsii-zone of Midford. Purpurina Belia, VOrb. (T. J, ii, pl. cecxxx, 
figs. 9, 10), is perhaps nearly the same. 
