XL] COMPARISON III 



with Dryopteris\ Fig. 654, C shows its sorus cut in the same direction as 

 that oi Peranema in A. On the other hand, the lop-sidedness of the sorus 

 finds its equivalent shghtly indicated among the Woodsieae, and in Henii- 

 telia among the Cyatheaceae, in both of which the indusium is deficient or 

 even absent on the side next to the leaf-margin. Lastly, the origin of the 

 stalk of the sorus in Peranema is due to late intercalary growth: apart from 

 this the sorus corresponds in all essentials to that of Dryopteris. 



The sporangia of Peranema are inconstant in their first segmentations : 

 sometimes the first cleavage is transverse, but usually it is oblique. The 

 adult sporangium has a three-rowed stalk, and the margin of the flattened 

 capsule is surrounded by a slightly oblique annulus with 12 to 14 indurated 

 cells. Sometimes the induration is continued past the insertion of the stalk, 

 but more commonly it stops in the cell just at its centre, though the series 

 of cells of the annulus is always continued past the stalk. The stomium has 

 two strongly indurated cells, between which the break occurs. The number 

 of spores is typically 64. These characters indicate an intermediate condition 

 between a gradate and a mixed type. The spores are "Aspidioid" in their 

 character (see Hannig, I.e. p. 340). 



Davie found the prothallus of Peranema to bear unicellular glandular 

 hairs both on the wings and on the cushion. The lid-cell of the antheridia 

 was seen, in every case observed but one, to be undivided. These details 

 accord with an intermediate state between the Cyatheoid and Dryopteroid 

 types, but with a leaning towards the latter. The general conclusion will be 

 that this position commonly assigned to Peranema is justified. 



Comparison 

 In Volume II a line of comparison among Ferns with consistently super- 

 ficial sori has been traced, starting from an ancient ex-indusiate type which 

 was frequent in Mesozoic times, and existed even in the Palaeozoic age, as 

 Oligoearpia (Fig. 493). It is represented at the present day by the Gleiche- 

 niaceae. In Chapter xxiv it was shown how the sub-genus Eii-Dicranopteris 

 stands apart from other living Gleicheniaceae in its more advanced vascular 

 condition, and in its dermal hairs; but more particularly in the more 

 numerous sporangia in the unprotected superficial sorus (Fig. 488), in the 

 smaller size of the individual sporangium (Fig. 489), in the smaller number 

 of the spore-mother-cells (Fig. 491), and consequently in the smaller output 

 of spores from each sporangium. The comparison was continued in 

 Chapter XXXII. Here the monotypic genera, LopJiosoria and Metaxya, still 

 ex-indusiate, and retaining certain other relatively primitive features, were 

 regarded as synthetic genera, linking up the superficial Simplices with the 

 Gradatae of this whole phylum, and in particular the Gleicheniaceae with the 

 Cyatheaceae. On that account they were designated the Protocyatheaceae. 



