RADSTOCK SERIES OF THE SOMERSET AND BRISTOL COAL FIELD. 389 



Bhacophyllum spinosum, Lesquereux. 

 Plate XX. fig. 3. 



Rhaeophyllum spinosum, Lesqx., Coal Flora of Pennsyl., p. 320, pi. lviii. figs. 4, 5. 



Description. — Frond tripinnate, pinnae alternate, diverging from the broad 

 flat membranous rachis at an acute angle ; pinnules alternate, lanceolate, of 

 delicate texture, with 2-3 short spine-like teeth, and a prominent lanceolate 

 terminal lobe. In the centre of the flattened membranous rachis of the pinnae 

 is a nerve, from which simple veins are given off to each pinnule, in which 

 again a single veinlet seems to extend into each tooth. 



Remarks. — The above description varies somewhat from that given by 

 Lesquereux in his Coal Flora, p. 320. It is there stated — " The veins are 

 clearly seen in parallel fascicles on the rachis, and may be followed into the 

 lateral pinnae, where they disappear, probably there dividing into very thin 

 branches, and passing into the lobes." " The rachis is distinctly dotted." 



In comparing the outline and general form of the Radstock example with 

 Lesquereux's figures, especially with his figure 5, the identity of the two ferns 

 is complete, the only differences between them being the simple veins in the 

 Radstock specimen, and the absence of the dots on the rachis. In the Rad- 

 stock example, unfortunately, the main rachis is almost entirely removed, and 

 only a faint indication of it is given on the matrix. The scales, however, 

 might have been shown on the rachis of the pinnae, but there is no indication 

 of their presence, — but this is a character of secondary importance, as their 

 presence or absence dej^ends so much on the part of the frond under examina- 

 tion, and the state of preservation of the fossil. 



In regard to the discrepancy in the nervation, the specimen I figure shows 

 clearly that a single vein penetrates the centre of the broad membranous 

 rachis of the pinnae, which gives off to each pinnule a similar single vein ; I 

 could further distinguish the presence of a single veinlet in the teeth of some 

 of the pinnules. 



I am, therefore, led to conclude that what has been regarded as veins 

 by Lesquereux are only external striae, and this view is strengthened from 

 the examination of the last species (R. Goldenbergii), which belongs to the 

 same group of Rhacophylli, and where the veins are of a similar simple 

 nature as those occurring in the Radstock specimen of Rhacophyllum spinosum, 

 Lesqx. 



The only example of this fern that I have seen is that figured on Plate XX. 

 fig. 3; it is in the collection of Mr J. M'Murtrie, F.Gr.S., who has kindly 

 submitted it to me for examination and description. 



Locality : — Radstock. 



