358 THE BOOK OF CHOICE FERNS. 



species may be said to be very similar to that of Hymenophyllum, to which, 

 so far as outward appearances only are concerned, Trichomanes bear a very 

 great resemblance. The plants forming this genus also agree with the 

 Hymenophyllums in habit of growth and in delicacy of texture, the 

 character furnished by the shape of the involucre dividing a very natural 

 tribe into two nearly equal halves. In Trichomanes, as in Hymenophyllum, 

 the fronds vary in shape and cutting from simple (undivided) to decompound- 

 multifid (many times divided), and the sori (spore masses) are marginal, 

 always terminating a vein, and more or less sunk in the frond. The 

 involucre and receptacle, however, are different : the former is tubular, closely 

 corresponding with the frond in texture, with its mouth either truncated, 

 winged, or slightly two-lipped ; the latter, as fine as a thread, is elongated, 

 often extending considerably beyond the mouth of the involucre, and shows, 

 especially at the base, some stalkless, depressed capsules surrounded by an 

 entire, broad, nearly transverse ring, bursting vertically. 



In the " Synopsis Filicum," the genus Trichomanes is divided into two 

 sub-genera as follow : 



Feea (Fe'-e-a), Van den Bosch. The plants in this sub-genus produce 

 barren and fertile fronds entirely distinct. While the former are pinnatifid 

 (deeply cleft nearly to the midrib), the latter consist simply of a narrow, 

 distichous spike, formed of two rows of spore masses regularly disposed on 

 the two opposite sides of a common axis or midrib. 



EuTKiCHOMANES (Eu'-trich-om'-an-es), or true Trichomanes. This, as 

 stated in the " Synopsis FiHcum " (p. 72), includes numerous genera of 

 Presl and Van den Bosch, founded primarily on the texture of the frond 

 (whether it is composed of one or of more than one layer of cellules) ; 

 secondarily, upon whether the mouth of the involucre is entire or two- 

 lipped ; and, thirdly, on the degree to which the frond is divided and the 

 character of the venation, Eutrichomanes is by far the most important 

 sub-genus ; it is composed of plants with barren and fertile fronds 

 uniform" or nearly so, and comprises : 



(1) Plants with fronds entire or slightly lobed, without a distinct central 

 midrib, the veins radiating from the base in a fan-like manner. This 

 section is best represented by the popular "New Zealand Kidney Fern," 

 T. reniforme. 



