io8 Alexander W. Evans, 



striking-; but in any case it easily becomes detached as the sporo- 

 phyte approaches maturity. Below the corona the surface of the 

 calyptra varies greatly when different species are compared. 

 Sometimes the surface remains smooth or nearly so but it is much 

 more likely to become roughened, either through the splitting off 

 of the superficial cells or through the presence of true appendicu- 

 lar outgrowths. It is not unusual, moreover, for one or more 

 unfertilized archegonia to be carried up by the growth of the 

 calyptra, although these usually remain in the basal portion. 



The characteristic gemmae of Riccardia have long been known 

 (see Goebel, 12, p. 671, /. 628). They are in the form of oval 

 two-celled bodies, which arise singly inside cells on the dorsal 

 surface of the thallus or along the margin. When the gemmae 

 are mature, the walls of the cells containing them are split, and the 

 gemmae are set free. The branches bearing gemmae are slightly 

 or not at all dift'erentiated, so far as known, but they are usually 

 quickly limited in their growth. Sometimes the gemmae are so 

 abundantly produced that the branches seem to be covered over 

 with a fine green dust. 



The Chilean specimens studied have been too incomplete to 

 throw much light on the structure of the sporophyte, but a few 

 words regarding its distinctive features may be included. The 

 capsule is of especial interest, owing to the comparatively small 

 space occupied by the sporogenous tissue in the early stages of 

 development. This space, as shown by Goebel and others (11, 

 /. 2ip; 6, pi. II, f. 142), is in the form of a hollow sphere or 

 ellipsoid open at the top. The interior is occupied by the young 

 elaterophore, which extends through the apical opening of the 

 mass of sporogenous tissue and becomes continuous with the 

 young wall cells at the tip of the capsule. As development pro- 

 . ceeds, the sporogenous tissue grows more rapidly than the elatero- 

 phore and occupies a much larger proportion of the space enclosed 

 by the capsule wall. At maturity the wall dehisces in the usual 

 way into four valves, each carrying at its tip a portion of the 

 elaterophore. The cells of the latter have annular or half-annular 

 thickenings in their walls, their free extremities often showing 

 single spirals. In this respect they resemble the true elaters, 

 which are long and pointed cells, each one usually with a single 

 broad spiral band of thickening. The cells of the capsule wall 



