520 Proceedings of the Royal Physical Society. 



apparently produced on the upperside of the rachis-like vein 

 of the very much metamorphosed pinnules, which in this 

 case almost assume the structure of pinnae, though their 

 being only modified pinnules is proved by their position and 

 by the occasional occurrence of a few sporangia on the 

 margin of some of the foliage-pinnules, which, in the few 

 such cases observed, had undergone but little reduction in 

 the limb of the pinnule. A similar production of sporangia 

 on the incompletely modified foliage-pinnules is not un- 

 common in Osmunda regalis. The fruiting-pinnules end in 

 several simple or divided thread-like filaments. The fruit 

 appears to consist of exannulate Marattiaceous sporangia. 



Another interesting point was observed on some of the 

 specimens in the collection of the Geological Survey of 

 Ireland. This had evidently been noticed by Mr Baily, 

 though its importance was not fully appreciated, and is 

 referred to by him as a rounded expansion of the base of the 

 stem, which apparently separated into scales. Mr Carruthers, 

 evidently referring to the same structure, says, " The stipes 

 were thick, of considerable length, and clothed with large 

 scales, which formed a dense covering at the enlarged base." ^ 



The structures here alluded to are two large stiioules, one 

 on each side of the base of the rachis, and on some of the 

 specimens in the collection of the Geological Survey of 

 Ireland they are admirably shown. What has given rise to 

 the statement that the base of the stipe was " clothed with 

 large scales " is evidently the remains of large pinnules which 

 are situated on the main rachis between the pinnse, and are 

 continued to almost the extreme basal termination of the 

 rachis. Sach pinnules, obliquely imbedded in the matrix 

 and broken over, have been mistaken for scales. So far as 

 my observations have gone, the rachis is entirely destitute 

 of membranous scales. 



The presence of the stipules at the base of the rachis of 

 Archoeopteris hihernica, altogether independently of the 

 evidence afforded by the fruit, points strongly to its affinities 

 being with the Marattiacese ; and when to this is added the 

 Marattiaceous structure of the fruit itself, there does not 



^ Cavnitliers, I. c. 



