2 SMJ TIISONIAN MISf'KLLANICOUS COI.LliCTIONS VOL. 66 



surfaces, wliili- llu' axils of the secomlary and Iciiiary lachises and 

 the narrow furrows of the vascular parts al)ove .are more or less 

 llllfd with a short rufous puhesceuce consisting of short, few-celled 

 artii idalt* hairs; a few similar hairs are found on the veins heiieath. 



I hii',, III [iiilifscence the leaves agree perfectly with those of I'oly- 

 botrya osiHnndacea, while the leaves of the species of Dryopteris and 

 I'olystictiutn ahove mentioned are scaly or dilterently hairy. 



The fertile leaves also are very different from those of Folystichum 

 adiantiformi' and all species of Dryopteris. Their leafy parts are 

 often so greatly contracted that the whole leaf resemhles a mere 

 skelet(»ii consisting only of the vascular parts, which hear the sori. 



Thus the leitile leaf ri'seinhles not a little that of l'ol\hoirya osinun- 

 iliiit'd, allhouj-di Usually it is not so nuich conlrac-led. There is, how- 

 ever, a very important dilference. The sori are confined to the veins 

 aii<l are iiidnsiale, whereas in l\>l\b()trya the sporangia an- borne on 

 almost the whole under surface of the fertile lobes and are not 

 covered by an indusinm. Most specimens seen have the leaves 

 strongly dunoiplions, but this character is not a stable one. 1 have 

 two specimens, for examjjle, in which certain parts of the leaves 

 (mainly the upper half) are fertile, while the lower part is sterile; 

 ilie lertile segments are nt)t luaily so iihh b idiitractetl as is the case 

 in the entirely dimorphous form. 



The indusium of /*. apiifoliitni is very peculiar, and uni(|ue in its 

 development. This is seen very beautifull\' in a specimen from 

 Jamaica {Ma.von 2284a). In its fust stale the indusinm is seen as a 

 little protuberance on the back of a vein, sometimes immediately 

 below its a|>e\. This profubi-rance elongates toward the vein-tip and 

 loinis a jiale liiuai body, paiallrl to tlu- vein aiul raiseil ahove it. It 

 soon broadens at its outer part, becoming spatulate; and as growth 

 proceeds the margins bend downward and linally are firmly appressed 

 to the pareiK bynia of the \ein. In this state the indusium resembles 

 much that of Cystopteris or sometimes that of Davallia; and now the 

 tirsi traces of the sporangia are seen on the vein immediately above 

 tin- base of the indusium. This, however, continues its growth at 

 the sides, scarcely at the apex, and thus soon becomes rounded at 

 the outer edge, its shape being now nearly circular, with a short, 

 cuneate base, its pedicel. Next the basal part of each side grows out 

 inl(» a ronnded lobe, direited backward. I'he indusium has now 

 become 1 eddish brown, subreniform (the basal sinus being low 

 only), and highly vaulted over the sporangia, around which it is 



