INTRODUCTION TO CllYPTOGAMIC BOTANY. 



875 



development of the filamentous element of Strigula, a genus 

 in which the cortical element usually prevails. Gwnogoniuin, 

 on the contrary, appears to be a normal form, remarkable for 

 the almost total suppression of the ujitper stratum. The place 

 of growth is similar to that of Dlctyonema, and its habit is 

 very much the same. It is just possible that the various 

 species of Chroolepus, which have some resemblance to Cepha- 

 leurus (Fig. 81, a), may be peculiar states of certain Lichens, 

 their reproductive bodies being very similar. 



Fig. 79. 



a. Section of a Collema, sliowiug new frouJs arising from the sur- 

 face. From Noukabeva. 



h. Sporidium of Biatoru marginijiexa, Bab. From New Zealand. 

 Communicated by Dr. Hooker. 



c. Leptoghim hullatum, showing a section of one of the a])thou9 pro- 

 cesses with its fertile disc, the sporidia and external cells of the 

 frond. More or less magnified. From Assam. Communicated by Dr. 

 Hooker. It is the form figured by Swartz, in Lich. Amer. 



411. If the Collemals are associated with Lichens, which 

 appears to me the most natural arrangement, we have still, in 

 most cases, the medullary and cortical layers with gonidia, dis- 

 posed frequently in long moniliform threads (Fig. 79, a) ; but we 

 have in addition an abundant gelatinous element, in consequence 

 of which, many are hard and rigid when dry, and when moist- 

 ened resemble closely some of the Algaj. Indeed, some states 



