252 Transactions. — Geology. 



determine it exactly, and to ascertain its most nearly related 

 living species, as not only the nervation but also the fructi- 

 fication is distinctly preserved. The fronds indicate a gradual 

 narrowing towards the top, hut on the whole a linear form. 

 The division of the foliage is deep towards the base, but less 

 incised towards the top, as the sections of the frond arc ovate, 

 sometimes elongated, and the edge is without indentations or 

 notches, becoming smaller and stumpy tow'ards the top. The 

 nervation, which is well preserved in the fragment from Dun- 

 stan, fig. 4 (enlarged, fig. 4a), shows a strongly-defined primary 

 nerve, which runs straight and gradually decreases, and from 

 which sharply-defined secondary nerves start at somewhat 

 acute angles. The tertiary nerves, which start at far more 

 acute angles, are simple : the lower are straight, the upper 

 somewhat converging and turning to the edge ; the lower- 

 most have anastomosis. The sori are situate in the middle of 

 the course of the tertiary nerves. 



Consequently this fossil would belong to the genus Lastrcea 

 according to A. Braun, in which the sori are said to exist mid- 

 way in the course of the tertiary nerves. This A. Braun 

 seems to have concluded from few specimens, which he more 

 closely examined, of the genus Asj^icUum, which has many 

 species ; but he is scarcely correct as regards all species, for in 

 A. oiypositum, Kaulf., andu4. truncatum, Gaud., the sori exist 

 nearer to the beginning of the tertiary nerves ; in ^, molle, Sw., 

 and A. concinnum, Mett., they are nearer the edge; while in 

 A. alsophilaceum, Kze., both conditions exist. In all these 

 species the sori exist also inserted in the middle of the tertiary 

 nerves. It does not occur in Aspidiuvi that the sori do not 

 exist between the tertiary nerves instead of on them or on 

 their branches. In consequence of this, Heer's drawing can- 

 not be correct which he gives of the situation of the sori 

 in liis A. meycri ("Tertiary Flora of Switzerland," i., pi. 11, 

 fig. 26). 



The characteristics described do not agree so well with any 

 species of fern as Aspidiuvi novos-zcelandice (Goniopteris n.z., 

 Presl., see Ettings., Ferns, pi. ex., figs. 12, 13), which is indi- 

 genous to New Zealand, and for which our fossil may pass as 

 the parent plant. The latter seems to be distinguished from 

 the former by the more stumpy and more rounded sections 

 of the frond. Moreover, the sori in A. novce-zcelandia are 

 seldom in the middle, but usually near the origin of the tertiary 

 nerves. Sufficient material has not been submitted to make a 

 searching comparison of this fossil with other fossil ferns 

 already known. A second fragment comes from the strata at 

 Shag Point, in which I observe deeper notches in the frond, 

 the segments of which are more distant from each other ; 

 moreover, the angle at the origin of the secondary nerves is 



