BY R. ETHERIDGE, JUX. 
i3oa 
but very slowly in width towards their apices. The pinnules are 
ovate or obovate-pyriform, and retain their form thi’oughout the 
length of each pinna, until near their apices, when the pinnules 
l )ecome longer and more wedge-shaped, the pinna terminating in a 
uni-, bi-, or tri-lobed pinnule. The pinnules have likewise a some- 
what tlabellate aspect, seldom sub-imbricate, or overlapping one 
another, but separated by an interspace, which is certainly at 
times rather inconspicuous. The proximal margins of the pin- 
nules are parallel to the ra<4iis, and during fossilization some of 
tliem have slightly infringed on the latter. 
The two lowest pinme exhibit a marked dilierence from those 
above them. The second pair are the best preserved, and are 
deeply lobate and pinnatifid, conforming to the habit we are 
accustomed to associate with the pinnules in some Sphenopterids. 
The divisions of the pinme in question have quite lost their 
pyriform, or obovate outline ; but are irregularly trilobate, and to 
some extent incised, the apical lobe being the largest, and more or 
less lanceolate. The nerves are but very faintly visible on the 
specimen occupying the greater portion of the slab, but are shown 
on a smaller example lying near. The lower pinnse seem to be 
only a moditication of the lobate apical pinnules of the higher 
pinme, as seen on the tliird to the right from the bottom of the 
specimen, and the fifth and sixth on the left hand. But they are 
not the basal, as the lower portion of the frond is concealed l>y 
matrix. 
The resemVdance of A. auatrina to A. adiantovhs consists in the 
similar obovate or pyriform pinnules, with a like moditication 
of the apical pinnules. The two ferns, however, differ greatly in 
the relative sizes of their respective portions, whilst in the British 
species there is no appearance of the dissimilar lower pinme. 
From A. Dn., the form of the pinnules will at once 
distinguish it. 
