398 Dr. Falconer on Athalamia, a new Genus of Marchantieoe. 



opening at the top into two concave valves, with the slit of dehiscence extending lower 

 on the outside; continued downwards on the inside in a slightly-keeled ridge descend- 

 ing to the point of confluence. Calyptra persistent, somewhat funnel-shaped, divided 

 vertically about half-way down into two lacerated valves, reaching about half-way up 

 the pedicel. Sporangium globose, somewhat compressed at the sides, opening into 4, 

 or generally 5 subequal segments, which are at first explanate, and at length revolute : 

 in the ripe state the sporangium is just protruded beyond the summit of the involucella. 

 Pedicel thick, smooth and cylindrical like the peduncle, fully the length of the involu- 

 cellum, slightly bulbose at its base where inserted on the peduncle. Spores very 

 numerous, nearly globose, of a light brown, with the sporoderm slightly dilated into a 

 toothleted wing beyond the nucleus, mixed with elaters. 

 Obs. Only seen in the ripe state, with the frond beginning to wither. The so-called male 

 flowers were not made out. One of the lobes of the calyptra terminated by a filamentous 

 process. 



Apparently an undescribed and very distinct genus, characterized by the 

 absence of a common receptacle and the erect flowers : most nearly allied to 

 Lunularia, in the dehiscence of the sporangium and elongated pedicel. 



EXPLANATION OF PLATE XIX. 



Fig. 1. Athalamia pinguis, Falc, of the natural size. 



Fig. 2. One of the sporangia, with its 2-valved involucellum. 



Fig. 3. The same, opened to show the calyptra. 



Fig. 4. A 3-flowered pedunculus, with the sporangia unopened. 



Fig. 5. The same, after dehiscence of the sporangia. 



Fig. 6. A sporule, with its dilated margin. 



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