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.). 

 FIG. 4 (V. 2159). FIG. 5 (V. 2159). 



Enlarged 3 times. Enlarged 3| times. 



Among recent ferns there can be little doubt that Onychium 

 comes nearest to 0. Mantelli 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 Onychium. The flat and thin margin 

 in all probability corresponds to the flattened indusium border in 

 the recent genus. Fee's figures of Onychium 1 show very clearly 

 the character of the fertile pinnules. Some specimens of Onychium 

 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 Fee, Genera Filicum, pi. vii. c. 



