47-i Prof. F. IM'Coy on some new Silurian Radiuta. 



satisfy inyself from the authentic but imperfect specimen I exa- 

 mined a few days ago in the late Mr. Brodie^s herbarium. I 

 may here mention that a small mountain state of A. dilatatum 

 has the scales of the stipes uniform in colour^ or so nearly so 

 that the dark centre is undistinguishable ; and that the glands 

 on the under side of the frond may be perceived in both L. dila- 

 tata and recurva, although often wanting in the former. 



When correcting p. 358 of the ' Flora/ I ought to have stated 

 that I had seen no authentic specimens of Rumex pratensis ; since 

 then Mr. Borrer pointed out to me, at Killin, a plant which he 

 called so, and I find that I had long ago collected the same in 

 other parts of Perthshire, as in Glen Farg ; at present I am 

 disposed to look upon it as a hybrid between R. obtusifolius and 

 R. crispus, with both of which it was growing : and I may add, 

 that about six weeks ago I found in Kinross-shire what I con- 

 ceive to be also a hybrid between R. obtusifolius and R. aquations, 

 differing from the R. pratensis by the sepals almost as large and 

 as cordate as in R. aquaticus : this last hybrid rarely perfects its 

 achenes, perhaps never, for although some of them appear mature, 

 they may not spring when sown : if they do, or if even only one 

 does, I expect the offspring to produce perfect seeds more readily 

 than the original plants, till ultimately it may be ranked as a 

 species by those who have not traced its history, — as good a spe- 

 cies, at least, as many others in the European Flora, upon which 

 we only pronounce by de prcesenti observations without the aid 

 of analogy and theory. 



Yours, &c., 



G. A. Walker-Arnott. 



XLII. — On some new Silurian Radiata. By Frederick M'Coy, 

 Professor of Geology and Mineralogy in Queen's College, 

 .Belfast. 



To the Editors of the Annals of Natural History. 



Gentlemen, Queen's College, Belfast, Nov. 16, 1850. 



In my paper in the 'Annals' for October, the following few spe- 

 cies were by some accident omitted. 



I have the honour to remain. Gentlemen, 



Your most obliged and obedient servant, 



Frederick M'Coy. 



Strephodes pseudo-ceratites (M'Coy). 

 Sp. Char. Corallum small, simple, curved, conical, obscurely 

 wrinkled concentrically; ordinary specimens about 1 inch 

 3 lines long, and 9 lines in diameter at that distance from the 



