THE BRIAN OR DEVONIAN FORESTS. 



97 



committal, is tho.-eforo. T ihink, to be preferrcfl. In my "Acadian 

 Geolojjy," and in my "Kiporr on the GeoIoj?y of Prince Edward 

 Island,'' I have given reasons for hclievinj? tliat the foliage of some 

 at least of these trees was that known w. Walrhm, and that they may 

 have borne nutlets in the manner of Taxiue trees (7V/(70Hocnr/>»/m, 

 &c.). Grand d'Eury has recently suggested that some of them may 

 liave belonged to Cordnites, or to plants included in that somewhat 

 varied and probably artificial group. 



The earliest discovery of trees of this kind in the Erian of 

 America was that of Matthew and Ilartt, who found large trunks, 

 which I afterwards described as Dadoi-yUm Ouangnnd ianum, in the 

 Erian sandstone of St. John, New Brunswick, hence named by those 

 geologists the " Dadoxylon sandstone." A little later, similar wood 

 was found by Prof. Hall and Prof. Newberry in the Hamilton group 

 of New York and Ohio^ and the allied wood of the genus Ormoinjlon 

 was obtained by Prof. Hall in the Portage group of the former 

 State. These woods proved to be specifically distinct from that of 

 St. John, and wore named by me T). Halli, D. Newberryi, and Or- 

 moxylon Eriaiuim. The three species of Dadojryhm agreed in hav- 

 ing composite medullary rays, and would thus belong to the group 

 Palfpoxyfon of Brongniart. In the case of Ormoxylon this character 

 could not be very distinctly ascertained, but the medullary rays 

 appeared to be simple. 



I am indebted to Prof. J. M. Clarke, of Amherst College, Massa- 

 chusetts, for some well-preserved specimens of another species from 

 the Genesee shale of Canandaigua, New York. They show small 

 stems or branches, with a cellular pith surrounded with wood of 

 coniferous type, showing two to three rows of slit-formed, bordered 

 pores in hexagonal borders. The medullary sheath consists of 

 pseudo-scalariform and reticulated fibres ; but the most remarkable 

 feature of this wood is the structure of the medullary rays, which 

 are very frequent, but short and simple, sometimes having as few 

 as four cells superimposed. This is a character not before observed 

 in coniferous trees of so great age, and allies this Middle Erian 

 form with some Carboniferous woods which have been supposed to 

 belong to Cordailes or Siyillaria. In any case this structure is new, 

 and I have named the species Dadoxylon Clnrkiiy after its discoverer. 

 The specimens occur, according to Prof. Clarke, in a calcareous layer 

 which is filled with the minute shells of Styliola fissure.lla of Hall, 

 believed to be a Pteropod ; and containing also shells of Goniatites 

 and Gyroceras. The stems found are only a few inches in diameter, 

 but may be branches of larger trees. 



