40 BKITISH HEPATIC^. 



as if these stems bad outgrown tlie leaves." On the ultimate ramuli 

 we find them very regularly and closely imbricated, forming a 

 beautiful object under a low power of the microscope. At the 

 apex of the main shoots (especially in fertile individuals), the 

 leaves are remarkably crowded together, forming a kind of baU 

 or tuft. Form. Erom a contracted entire base, each leaf divides 

 into two multifid main lobes, the anterior smaller and ovate in 

 outline, the posterior larger and rounded ; each lobe again is cleft 

 into numerous setaceous capillary segments (f. 32, 3), the main 

 ramules bearing short opposite lateral processes, so as to " give a 

 peculiar tomentose appearance to the whole plant, and render the 

 true figure of the leaf difficult to define." 



AmpJiigastria. Between each pair of leaves, and generally con- 

 fluent with the left-hand one, we find an amphigastrium (f. 32, 5), 

 subquadrate in form, about equal in diameter to the stem, the lower 

 half entire, and the margin cut into numerous ciliary processes, 

 but shorter and less branched than those of the leaves. 



Texture. The terminal segments of the leaf consist of a series 

 of 3 to 5 oblong cells (f. 32, 3), which are jointed in outline, as in 

 Jung. tricophyUa and many confervse, the larger segments con- 

 sisting of two, or four rows of cells. The walls are clear, and not 

 thickened at the angles, the interior filled with pale green chloro- 

 phyll granules. Length of apical cells -g-^" to ■^\-q", breadth about 

 x^jTo " J the basal cells are about Y^ta" ii diameter. The epidermic 

 layer covering the cells is delicately striate-punctate, which may 

 account for the dull frosted appearance under direct light. 



Inflorescence dioicous. Pertile shoots thickened at the apex. 



Involucre (f. .32, 1, 6) xo" to xs" in length, clavate, sub-carnose, 

 resembling the stem in texture, of which, indeed, it may be consi- 

 dered a hollow prolongation, clothed more or less densely by jointed 

 tomentose bracts, which are most abundant at the base (f. 32, 4). 



Calyptra connate with the involucral walls, and bearing at the 

 apex the abortive pistillidia (f. 32, 4). 



Fistillidia very numerous, at first naked, and surrounded by 

 the circle of involucral bracts, as shown in Dr. Gottsche's figure, 

 Hep. Eur. Ex. t. 272. After impregnation, by the rapid upgrowth 

 of the cortical layer of the stem, only the dome-like apex of the 

 calyptra remains free, and is pushed outwards by the emerging 

 capsule. In one or two instances of nearly mature fructification, 

 I have found no difficulty in separating the calyptra from the invo- 

 lucral walls, but generally (invariably in T. tomentosa and other 

 exotic forms) the two are so blended together as to constitute only 

 one membrane. 



Capsule (f. 32, 6) ovate-oblong, of a deep purple-brown, longitu- 

 dinally and transversely striate, dividing into four oblong valves. 



Peduncle fleshy, an inch or more in length, dilated at the base, 

 where it is inserted into the substance of the thalamium. 



