INTRODUCTION. 



or keeled, and may, or may not, be toothed or 

 fringed at the mouth. At this time it encloses the 

 fertilized archegonium, now developed into a sporo- 

 gonium, with a rudimentary pedicel, which is 

 enclosed within a membrane, attached at the base 

 and pointed at the apex, called a calyptra. This is 

 not to be confounded with the hood, or calyptra, in 

 mosses, which is torn away at the base and carried 

 up, like a cap or extinguisher, on the top of the 

 capsule. In Hepatics the calyptra remains fixed 

 at the base and is ruptured at the apex, leaving the 

 fragments behind, in the perianth, surrounding the 

 base of the fruit stalk. With the rupture of the 

 calyptra the sporogonium is forced upwards by the 

 growth of its peduncle, and appears above the 

 perianth as a globose head (fig. 12), which soon 



14. 



splits, in a stellate manner, into four segments or 

 valves (fig. 13), leaving the remains of the calyptra 



