BRITISH HEPATICiB. 15 



less compressed, naked at the base, or when prostrate, clothed with 

 rootlets on the underside. Stolons about the thickness of horse- 

 hair, branched and rigid, here and there attached to the ground by 

 capillary fibres. 



Leaves |^ to ^ a line in length, usually broader than long, cor- 

 date-orbiculate, occasionally sub-quadrate, in the smaller forms 

 nearly circular ; apex divided by an acute but shallow notch into 

 two equal obtuse (f. 7, 5, 6) or abruptly-pointed lobes (f. 7, 3, 4) 

 equal to ^th or ^th of the length of the leaf. 



On the lower part of the stem (f. 7, 2) the leaves are more 

 distant, and patent or divergent, but towards the apex more closely 

 imbricated, nearly vertical, very concave, rounded at the base, 

 amplexicaul, the lateral margins narrowly recurved, except at the 

 upper third. 



Texture firm and sub-cartilaginous, polished, little altered when 

 dry; pellucid punctate. Marginal cells smaller, sub-quadrate, 

 stt" l>y iTTe " J cells of the upper third hexagonal (f. 7, 12), j^" 

 to to" I'y ttt" ; Ji^ar the base the cells elongate, and the trigones 

 are less regularly disposed, -j-^" by -gio". Trigones about ttwq"' 

 In the var. robusta the measurements are nearly the same, ttso" 

 to -g-fro" ill length and x\6q " broad. In var. minor the cells are some- 

 what smaller, and the marginal ones less regularly disposed. 



Colour variable, pale olivcryellow, or olive-brown, sometimes 

 tinged with red or purple. Specimens growing in water are of a 

 dark sordid green, or nearly black. 



Dioicous. Involucral leaves, 2 to 4 pairs, sometimes smaller 

 and more erect than the upper stem-leaves, but generally larger 

 and more deeply and acutely emarginate, occasionally with a third 

 lobe, the upper leaf frequently adnate at the base with the walls of 

 the involucre. 



Involucre terminal, or from the growth of innovations appearing 

 axillary, urceolate, formed of two leaves united together for half or 

 two-thirds of their length, and adnate with the colesule, the teeth 

 of which alone are free (f. 7, 7). On longitudinal section, the fruit 

 rudiment seems to be placed within a hollow scooped out of the 

 apex of the stem, and surmounted by the involucral bracts. If we 

 compress this organ, so as to view it laterally by transmitted light, 

 the structure is very evident (f. 7, 7, 8). The lobes of the involucre 

 resemble ordinary leaves, and between them, on the ventral aspect, 

 a smaller lobe may be observed, ovate, and entire or bifid at the 

 apex (amphigastrium). 



Teeth of the colesule at first connivent, afterwards splitting into 

 4 or 5 triangular lobes. 



Capsule spherical, rather small for the size of the plant, of a 

 pale brown colour, dividing into four ovate valves, which are of 

 firm consistence. Fedicel succulent, white, seldom exceeding half 

 an inch in length. 



