HALLE, ON THE SPORANGIA OF SOME MESOZOIC FERNS. 21 



whether it was complete or not. The aniiiilus seems to have 

 been somewhat twisted, as in Dictyojihyllinn, and probably it 

 was of the same general type as in that genus. The number 

 of cells in the preserved part of the annulus is about 10 — 12 

 in the semicircle. 



It is possible to remove the sporangia from the rock, but 

 on account of their croAvded position in the sori, it is very 

 difficult to isolate single sporangia from the rest. In a feAV 

 cases, however, this was possible, and the spores of each spor- 

 angium could then be counted after the usual treatment with 

 .Schultzens mixture and ammonia. Unfortunately the spores 

 cannot always be separated from each other but partly remain 

 packed in dense clusters which renders the counting very 

 difficult. The figures are therefore not very accurate, yet they 

 may be held to give a general idea of the spore-output. As the 

 result of a counting of the spores in four sporangia the following 

 figures were obtained: 42, 52, 57, 99. The tyi)ical number of 

 spores in each sjjorangium would thus seem to be 64 to 128. It 

 is i^ossible that the high figure of 99 which was found in one 

 case may be due to a superimposition of two sporangia. In 

 order to decide on this point, it would have been desirable to 

 count the contents of a greater number of sporangia, but it 

 was not ix>ssible to isolate any more sporangia intact. 



The difference, in regard to the number of spores in each 

 sporangium, between Dictyophyllum exile and Hausmannia 

 Forchhammeri is considerable. The number of spores in 

 Dicfyojjhyllum exile (see above, p. 18) was found to corres- 

 pond in most cases to the typical number of 512, in Haus- 

 mannia Forchham7neri in three cases to 64, in one to 128. The 

 spore-output per sporangium in Hausiiiannia Forchhammeri is 

 well in accord with the idea that Hausmannia should be held 

 to be most closely related to the Dipteridinae. As far as our 

 present knowledge of Hausmannia extends, there is nothing to 

 prevent this genus being actually referred to the Dipteridinae, 

 except, perhaps, that the sporangia seem to be a little more 

 rounded. 



TliaumatopterJs (Göpp.) Natu. 



'J'he genus Thaumatopferis was instituted by Göfpert 

 in 1841. The type species Th. Miinsteri Görr., was later 



