474 Prof. F. M'Coy on some new Silurian Radiata. 



satisfy myself 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 oi 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. obtusifoUus 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 1 con- 

 ceive to be also a hybrid between R. obtusifoUus and R. aquaticus, 

 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 prasenti observations without the aid 

 of analogy and theory. 



Yours, &c., 



G. A. Walker-Arnott. 



XLII. — On some neiv 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 



