328 



rOIATODIACE.*:. 



Tlie rescLiiblance of this fern or Prosaptia contigua aacl species of the 

 subgeniis Cnjiytosonis, to which Polypodium ohliquatum belongs, is very remar- 

 kable, aucl of a kiud wliich no botauists ever cUsiiute. The haV)it auil shape 

 of frouds, ancl the structure of liairs, scales aucl rhizomes are all the same. 

 The hairs (Fig. 137-b) are very peculiar ; thcy consist of several elongated cells 

 arranged iu a single row with very tliick browuish walls. The scales arc also 

 very reniarkable, being composed of polygonal cells with rather tliick lirownisli 

 walls aiTauo-ed 



iu oue layer, 



and beset witli 



bristles on the 



outcr surface 



(Fig. 137-a). 



Prosaptia, as 



stated above, 



closely reseiu- 



bles Polypo- 



dium decres- 



cens. Tlu^ 



scales of tlie 



latter cliffcr 



from those of 



the former ou- 



ly in hicking 



liristles. Tliese 



atliuities iu 



their anatomy 



all iioiut to 



tlieir being 



cougeneric, as 



such a general agreement in character is oue of the most imjiortaut points in 



the classification of genera, as is shown by C. Christensen, aud others. The 



anatomical characters seen in the structure of liairs aud scales are mostly 



Fig. 137, a — f, Pubjpodium urccolare H.vyat\ ; :i, :i scalc uf rhizome; 

 b, basal i^ortion of a liriir on tlie stipe ; c, portion of a frond, showing the 

 venation ; d, portion of a pmna, secn from bclow, showinj tlie sori of the 

 type ; e, an earlier st.age of the sorus-development ; f, much more advanced 

 sori, part of iiivohicres taken ofT, showing tlie receptai'les ; p;, an earlier stage 

 of the sorus development of Pohjpodium obliqmttim ; h, nsarly the stxnie stage 

 iii Prosaplia cclebicum Blumk ; i, nearly the sarae .stage in Promplia Emer- 

 soni ; j, full grown sori of Davailia bulkUa ; k, very earlier stage of the sorus- 

 development in the same species, showing the sori of the ITumata-tyiie. 



I 



