with a proposed new Arrangement of the Genera. 53 



growth is resumed by the axis through the centre of the flower, 

 and a female flower produced at a considerable distance. It is 

 only such mosses as these that are strictly acrocarpous. In 

 Funaria hygromctrica, which in its mode of growth represents 

 most of the so-called acrocarpous mosses, the plant first forms a 

 male flower, then bears female flowers on innovations arising be- 

 low it : but if the female flower had been produced at the point 

 whence the innovation proceeded, without theinnovation, it must 

 have been considered pleurocarpous, as i^Eygodon compactus 

 (Hedwigia cestiva, Eng. Fl.) ; although it would in that case be 

 as much acrocarpous as it actually is. In Fissidens the flowers 

 are all terminal, or only the female terminal, or both sexes lateral; 

 both of which last cases occur at times in F. bryoides. In the 

 Hypnoid Mosses the mode of growth appears more complicated ; 

 the principal axis being in many respects like a rhizoma growing 

 at one end and decaying at the other, producing roots at the side 

 and not having the lower end of the axis divided into roots. 



The capsules of Mosses are either without a regular opening 

 and bursting at the sides, astomate ; or furnished with a persistent 

 or deciduous lid, operculum, which on its removal leaves the cap- 

 sules closed by a membrane, stomate : the mouth of the capsule 

 naked, gymnostomate ; or with highly hygroscopic teeth arising 

 from its inner walls, peristomate ; or with the sporular sac also 

 divided above into processes and cilia, diploperistomate. 



In some well-marked genera, as Encalypta, Orthotrichum and 

 Zygodon, there exist gymnostomate, peristomate and diploperi- 

 stomate species, too closely allied in all other respects to be sepa- 

 rated generically in any natural arrangement. In Weissia, inclu- 

 ding as of one genus, Astomum Mittenii, Phascum crispum, P. ros- 

 tellatum, and all the Hymenostoma, Gymnostoma, and Weissia of 

 ' Bryologia Europsea/ are seen species astomate, stomate, gymno- 

 stomate, and peristomate ; and most of these mosses without the 

 presence of fruit would be difficult enough to distinguish as spe- 

 cies, to say nothing of genera ; — from which the conclusion seems 

 evident, that as a more or less perfect series of progressive deve- 

 lopment from astomate to diploperistomate capsules may occur 

 in a single genus, so any degree of development less perfect than 

 the diploperistomate may be considered but an imperfect state 

 of that degree, and of no importance in generic distinctions 

 whenever it is possible to trace a higher. 



The calyptra consists of the enlarged upper part of the arche- 

 gonium, and is dimidiate, mitriform, or calymperoid, the last form 

 being as it were a large mitriform calyptra split on one side ; but 

 it well marks the few genera in which it is found. 



In the following arrangement, the plan of dividing the genera 

 into groups dependent on the form of the cells of the leaves, as 



