188'.).] NATURAL SCIENCES OF PHILADELPHIA. 281 



ally grows in the fissures of the bark, where it is extremely difficult 

 to detect except in the sunlight ; but having found it, when the mem- 

 branaceous lid has a golden or coppery metallic luster, the plant may 

 readily be determined in the sunlight in the field with a hand-lens, 

 minute though the sporangium may be. This lid generally dehisces 

 and may occasionally be seen hanging to one side of the sporangium 

 by a mere point ; rarely it bursts in the center leaving a lacerated 

 fringe around the edge of the cup. When the plants are found 

 quite old and weather-beaten the cup frequently has a regular, well- 

 defined circular edge, but oftener it is collapsed. The sporangium wall 

 is often quite thin at the base, sometimes longitudinally wrinkled, 

 and under the microscope appears to be covered with minute gran- 

 ulations, regularly distributed, not unlike the manner of warting of 

 the spores of many species. The middle portion has the deposits of 

 plasmodic refuse. The accompanying cut gives the outlines of the 

 various forms of sporangium and stipe. The plant has frequently 

 been found associated with Orthotri'-hia microcephala Wing., and 

 enough of each was gathered to send to Mr. J. B. Ellis for his N. A. 

 F. Consequently an occasional sporangium of Orcadella operculata 

 may be found on the bark of the specimen of Orthotrichia microcephala 

 and vice versa. 



This family seems to bridge, to a certain extent, the gap between 

 Rostafinski's orders Anemeae and Heterodermeae, as we here have a 

 stage between the uniform wall of Licea, Tubulina, etc., and the 

 lacerate upper wall of some species of Oribraria where the receptacle 

 is strongly developed and covered with minute granulations. The 

 epispore seems to be absolutely without thickenings even under very 

 high magnification. 



