50 ONYCHIOPSIS. 
An examination with a low magnifying power enables us to 
describe the fertile segments as swollen, narrow, ovate bodies, 
often prolonged at the apex into a delicate awn-like termination ; 
with rugose surfaces, a thin flattened margin, and occasionally 
a longitudinal median depression. The roughness of the surface 
on further enlargement, e.g. Fig. 4, resolves itself in some of the 
better specimens into small circular areas, which probably mark 
the position of sporangia. 
Fertile segments of Onychiopsis Mantelli (Brong.). 
Fie. 4 (V. 2159), Fie. 5 (V. 2159a). 
Enlarged 32 times. Enlarged 33 times. 
Among recent ferns there can be little doubt that Onychium 
comes nearest to O. Muantelli in the form of the fertile segments. 
The sporangia are clustered together in oval sori covered by an 
indusium, and often prolonged apically into a delicate appendage. 
The circular areas referred to in the fossil no doubt indicate 
sporangia, and the median groove seen in some cases, if not an 
accident of preservation, may correspond to a similarly situated 
depression in the sori of Onychiwm. The flat and thin margin 
in all probability corresponds to the flattened indusium border in 
the recent genus. Fée’s figures of Onychium’ show very clearly 
the character of the fertile pmnules. Some specimens of Onychiwm 
auratum, Kaulf., in the Botanical Department Herbarium of the 
British Museum show fertile segments strikingly similar in form 
to those of the Wealden fern; in the recent species the arrange- 
ment of these sporangiferous segments is looser and less compact 
and regular than those shown in Pl. III. Figs. 1 and 2. The recent 
1 Fée, Genera Filicum, pl. vii. ¢. 
