488 Walter Keeping — Fossils from Central Wales. 



Measurements of type. — Length 1-| inclies ; length of stalk, ^ inch; 

 breadth of stalk, 3 mm. ; breadth of branches, 2 mm. 



They occur as dark carbonaceous films upon the slates of Cwm 

 Rymlog, and the species is also represented amongst the narrow- 

 branched forms of Craiglais, Aberystwyth. 



Localities and Horizon. — In the Aberystwyth Grits and Metalli- 

 ferous Slates at Cwm Symlog ; near Lisburne Mine, Ystwyth Valley ; 

 Aberystwyth ; Clarach Valley (?) ; Tregaron ; Machynlleth ; Pennant 

 Valley, Llanbrynmaer. 



Another plant-like organism from the Aberystwyth grits of 

 Mynydd Bach consists of a delicate stalk, branching irregularly and 

 giving off occasional tufts of minor branches after the manner of 

 Oldhamia antiqua, PI. XT. Fig. 4, 



Palceochorda tardifurcata, n, sp. PI. XL Fig. 5. 



A strap-like plant, circular in section, but generally flattened by 

 rock pressure. The long simple undivided fronds, as much as a 

 foot long, are frequently seen lying in sinuous courses, interlacing 

 with one another upon the rock surfaces, and showing but little 

 variation in thickness throughout their length. Dichotomous divi- 

 sion is however clearly to be seen in many specimens, as in our 

 Figure, the angle of division being usually about 60°. 



Measurements. — Breadth of fronds 2-6 mm., usual breadth 3-4 mm. 



Localities. — Aberystwyth ; Clarach ; Llanbadarn ; S. of Corys ; 

 Morben ; Machynlleth; Cwm Symlog; Lampeter; East of Llan y 

 Mowddwy ; and many other places. 



Betiofucus extensus, nbv. gen. et sp. PI. XL Figs. 6, 7. 



A stout rope-net structure, the meshes usually measuring about an 

 inch across ; composed of solid bars which are circular in section 

 and about 3 mm. in diameter. The whole structure is very uniform 

 and regular, the bars being only slightly knotted, and in other 

 respects irregular here and there. 



These bodies are commonly found spread out, without apparent 

 limit, upon the under surfaces of the grits, where they are very con- 

 spicuous objects. One specimen only has been found to show the 

 young condition when the branching has a more ordinary plant-like 

 appearance (PI. XL Fig. 7). The meshes vary in shape, irregularly 

 hexagonal and circular forms being most frequent ; variations in size 

 also occur, the meshes being sometimes only half an inch in diameter. 

 A variety collected by Professor Hughes from Constitution Hill, 

 shows a remarkably regular net-structure built up of semicircular 

 bars. 



Localities and Horizon. — Aberystwyth Grits, Aberystwyth ; Pont 

 Faen, Machynlleth ; near Eglwys Newydd ; South of Corys ; Lam- 

 peter. 



Besides the well-marked structures above described, other bodies 

 occur, often in great profusion and, apparently, in fragmentary con- 

 dition, upon the surfaces of the grit bands. Some of these resemble 



