Colenso. — On the Ferns of Xeio Zealand. 217 



Zealand fern, A. affine of Hook. = A. setulosum, J. Sm., is 

 identical with A. diaphanum of Blurne. 



Be that as it may, those two ferns (A. diaphanum and A. setu- 

 losum) are very distinct from this little Adiantum here described. 



2. A. tuberosum, sp. nov. 



Plant very small, weak, sub-erect, gregarious, caespitose in 

 small tufts, 1^-2 (rarely 3) inches high; rhizome creeping, 

 pubescent, tuberous (also tire numerous long and slender branched 

 rootlets) with many little brown oblong and obovoid tubers 

 singly scattered, each producing a single frond. Stipe 1-2 

 inches, capillary, somewhat flexuous, sub-angular, smooth, 

 glossy, red-brown (as also rhachis and petioles), with a few small 

 narrow acute scales at base. Frond simple, narrow oblong- 

 ovate, 1 - li (rarely 2) inches long, 5-8 lines broad at base, 

 pinnate, mostly 5- (sometimes 7-) jugate ; pinna? alternate, dis- 

 tant, sub-reniforin-quadrilateral, petiolate, spreading, dull green, 

 glabrous, superior margin slightly arched, the inferior less so, 

 nearly straight ; apex broadly rounded ; base slightly excised ; 

 sometimes the bases of a pair of pinnae are imbricate ; the lowest 

 pair generally larger and sub-deflexed ; the upper pinnae sub- 

 cuneate ; the terminal one large 4-sided, obtuse ; minutely and 

 closely dotted (sab lente) with very short reddish-brown pube- 

 scence (or sub-papillose scurf) on the middle and basal portions 

 of pinnae under surface ; margins toothed-serrate, irregularly 

 sub-lobed. Veins distant, dichotomous, dark, coarse, rather pro- 

 minent, reaching to margins and forming acute teeth. Sori few, 

 small, distant, irregular, mostly 2-4, sometimes 5, on a pinna, 

 very rarely 0-7 on the lowest and largest one, extending round 

 apex, distant from margin and the margin deeply crenate ; the 

 terminal pinna bearing 4-6 sori. Involucre remform and sub- 

 reniform-orbicular, at first white and closely appressed, brown 

 contracted and sub-revolute in age ; sinus very large and broad. 



Hab. Woods near Ormondville, County of Waipawa : Mr. 

 A. Hamilton. 



Obs. This species is pretty closely allied to the preceding 

 one, but differs in several important characters. At first sight I 

 supposed it might be a still smaller state of that plant, but a 

 close examination with plenty of good living specimens in all 

 stages has convinced me of it being distinct. It is a much 

 smaller plant, of a simple unvarying form, with a different habit 

 of growth ; the several distinct tufts of fronds closely arising 

 from the hypogaeous rhizome resemble a broad fringe ; its 

 tuberous rhizome and rootlets is a peculiar and rather strange 

 character ; the pinnae are thicker, duller and of a different shape 

 with sharply toothed margins ; veins coarse, dark, and promi- 

 nent ; the ultimate pinna large and bearing sori all round on its 

 four sides ; sori few and distant ; involucre smaller and brown. 



