264 
Davie.— The Structure and 
a little to one side at its point of maximum curvature and then twisting 
back into the vertical position. This recalls the condition of Diacalpe , 
in which, though the annulus stops short of the stalk, it is so far twisted in 
its course that the two faces of the sporangium can be readily distinguished. 
Peranema has an oblique annulus, which always passes the insertion of 
the stalk, though it is not always indurated throughout its whole length. 
The presence of an oblique annulus in a Fern with a mixed sorus is only 
paralleled by the cases of Dipteris conjugata (Miss Armour, ’07) and 
Plagiogyria (Bower, TO). In Peranema , however, the obliquity is very 
slight and is accompanied by unmistakable vestiges of a Gradate condition. 
In the absence of developmental evidence it would seem that Peranema 
occupies sorally an intermediate position between the Gradatae and the 
Mixtae, combining the receptacle, the annulus, and the spore-output of the 
one with the sporangial succession of the other. Diacalpe is more distinctly 
related to the Mixtae, in receptacle, sporangial succession, and spore- 
output. The annulus, while vertical in insertion, still possesses a tendency 
to obliquity, which is seen, less highly developed, in the annulus of Dryo - 
pteris pulvinulifera . This affinity with Nephrodium is strengthened by the 
presence of hairs on the sporangial stalks in Diacalpe and in Nephrodium 
filix-mas. 
The spores in Perane7na and Diacalpe are distinctly ‘ aspidioid ’. But 
those of Diacalpe are more closely related to those of Nephrodium filix-mas 
than are those of Peranema. In Diacalpe warty protuberances are much 
more numerous than perispore flanges and papillate pitted areas. The 
spores of Dryopteris pulvinulifera occupy an intermediate position between 
those of Diacalpe and those of Peranema. They possess both warty 
protuberances and perispore flanges, but the warts are rather more numerous 
than the flanges. 
The characters of the gametophyte generation are only known for 
Diacalpe , but they make its affinity with the Cyatheaceae quite undoubted. 
On the whole, then, Peranema and Diacalpe occupy an intermediate 
position between the Cyatheaceae and certain phyla of Polypodiaceous 
character. With the former they are joined on the characters of the 
prothallus of Diacalpe and of the receptacle and annulus of Peranema ; 
with the latter they show affinity in the vascular anatomy, the sporangial 
succession in the sorus, the length of the sporangial stalks, and the characters 
of the spores. 
The affinity with the Aspidieae, and more particularly with the genus 
Nephrodium i which is suggested by their habit, has been confirmed in their 
dictyostelic vascular system, in the scales on petioles and raches, in the glands 
on leaves and leaf-stalks, in the mixed sequence of sporangia, in the hairs on 
the sporangial stalks in Diacalpe , and in the spore-markings in both Ferns. 
The natural position for Peranema and Diacalpe seems to be with 
