RADSTOCK SERIES OF THE SOMERSET AND BRISTOL COAL FIELD. 377 



general character of many of the specimens is identical with the figure given 

 by Artis. 



Pec. Miltoni, Artis, sp. (whatever view may be taken of the relationship of 

 Pec. abbreviata to it), is very polymorphic in the form and size of the pinnules. 

 Artis has only figured one condition of his plant, a condition which probably 

 corresponds to Brongniart's Pec. abbreviata, fig. 1. 



Brongniart gave several figures of his species, and these have been well 

 supplemented by Zeiller. # Forms corresponding to the figures of these 

 authors occur among the Yorkshire, Lancashire, and Derbyshire specimens of 

 Pec. Miltoni; in the barren condition, neither from the form of the pinnules 

 nor their nervation can I discover any fixed character by which Pec. abbreviata, 

 Brongt., can be separated from Pec. Miltoni, Artis, sp. 



The only remaining point of comparison is the fructification. On this 

 Artis says : — " Fructifications surrounding the leaflets near, but not entirely on 

 ike margin." And again — " The fructifications seated on the back of the leaves 

 are not so closely seated on the margin as is expressed in the plate." 



Many of the specimens of Pec. Miltoni which T have examined, from the 

 counties already mentioned, are in fruit, though none have been in a condition 

 to exhibit its minute structure, such as the number of sporangia that compose 

 the sori, or the shape of the individual sporangia. These specimens, however, 

 clearly indicate the position of the sori, which appear as little circular dots, as 

 shown in the woodcut, figs. 2 and 3. 



Fig. 2 is a pinnse from a Lancashire example ; fig. 3 from a Derbyshire 

 plant. On both, the position of the fruit, as clearly indicated, is not marginal. 

 In fact Artis, in referring to his own figure, clearly states that the fruit is not 

 so closely seated on the margin as is expressed on his plate. Now, if his 

 figure be carefully examined, it will be seen that on many of the pinnules the 

 fruit holds almost a central position between the margin and the midrib, and 

 certainly if it is not so near the margin as represented, it cannot be other than 

 situated almost midway between the midrib and the margin, and then the sori 

 will cover the whole of the under surface of the pinnule, as figured by ZEiLLER.t 

 In the pinnae, where the pinnules are united throughout the greater part of 

 their length, the fruit forms a single or double row along the midrib of the 

 pinnas ; or, in other words, the pinnules only bear one or two groups of sori, 

 situated at their base, as seen in woodcut, fig. 2. 



Fig. 3 shows two pinnules densely clothed on their upper surface with short 

 hairs,| which quite obliterate the veins. The fruit is seen as circular dots 

 holding a similar position to those figured on Pec. abbreviata by Zeiller. From 



* Flore foss. du Bassin liouil. d. Valenciennes, pi. xxiv. 



t Loc. cit, pi. xxiv. figs. 3, 4, 4a, 4b. 



X These are also present on most of the pinnae of the specimen from which fig. 1 was taken. 



