ON NEMATOPHYTON AND ALLIES. 



33 



So far as yet kuowu, the tniuks of Nematophytou are confined to the lower members. 



3. — Associated Organisms. 



The question naturally occurs with reference to a plant so widely distributed in space 

 and time, whether any other organs than the stem and roots have been preserved. 



Perhaps the most constantly associated body is that to which Hooker has given the 

 name Pachi/lheca, from the Ludlow boue beds, holding also fragments of Nematophyton, 

 and stems supposed to be those of land plants.' As described by Dr. Hooker, they are 

 spherical bodies, varying in size from one line to one-quarter of an inch, and must have 

 been hard and resisting, as they have sufiered no compression or distortion. This is 

 explained by the fact that their walls are fully twice as thick as the cavity they enclose, 

 and are composed of radiating cells closely placed together. Hooker names the species 

 P. Spliœrica. Subsequently, Mr. Charles Brougniart described specimens of similar struc- 

 ture from the Carboniferous under the name Mlheolesta. He regarded them as possibly 

 gymnospermous seeds." Similar fossils have been described by me from the Devonian of 

 Scotland, where they were collected by Eev. T. Brown. Still later I found these bodies 

 not ituncommou in the Silurian beds holding fragments of Nematophyton at Cape Bon 

 Ami, near Dalhousie, and at the Bordeaux quarry, while Hicks has found them in the 

 Corwen beds holding Nematophyton. It is farther to be observed that the radiating tubes 

 resemble those of Nematophyton, not merely in their form, but in their evidently excep- 

 tional density and durability. The minute rounded bodies observed by Etheridge in the 

 cells of the Corwen specimens, I take to be accidental and concretionary.^ 



This frequent association and similarity of structure leave no doubt in my mind that 

 these bodies were connected with Nematophyton, and probably its fruit, and that the 

 density and durability of the envelope or testa of these fruits was, as usually holds in 

 similar cases, intended to protect the nucleus of the seed, and possibly to adapt it to float- 

 age to a distance on water. Unfortunately, only the thick wall of these reproductive 



' Journal Geol. Society, vol. ix, p. 12. 

 ' Journal Geol. Society, Aug., 1881. 



VAnn. des Sciences Naturelles, vol. sx. 



Sec. IV, 1888. 5. 



