I02 Evolution and Distribution of Fishes 



After describing the lower and evidently marine beds 

 up to "calcareous shales and flags with Spirifera elevata" 

 they make the following remarks (p. 203) : "They are 

 immediately succeeded by the famous Ludlow Bone Bed 

 which is too well known to require description. It is best 

 developed at the lower end of the section, on the south 

 side of the road, where it is 2 J/^ feet above road-level, and 

 reaches a maximum thickness of nearly six inches. It is, 

 however, very commonly separated into two thin bands of 

 'bony' material, divided by a few inches of soft mud-stone. 

 In addition to the numerous fish remains which the Bone 

 Bed contains, we have identified Chonetes str'wtella, Orhi- 

 culoidea riigata and Orthis sp.; a similar fauna, with Bey- 

 ricliia in addition, being found in the softer mudstone 

 separating the "bony layers." And as to the higher or 

 Temeside group they write (p. 203) : — "Tenieside group. 

 The succeeding sandstones (Ea) differ somewhat in lith- 

 ology from beds" below. So the writers remark ^^They seem 

 to usher in new conditions; for, above the Ludlow bone- 

 beds, the articulate brachiopoda, so characteristic of the 

 lower beds, have almost disappeared, Lingulae and the 

 molluscan fauna alone remaining; and we therefore con- 

 sider that the dividing line between the Upper Ludlow and 

 Temeside Groups is best drawn at this horizon." Next 

 (p. 205) : "The overlying grit-bed which is conspicuously 

 'bony' at its lower and upper limits, is here seen at its 

 maximum development (2 feet), but, like the other Bone- 

 Beds of this Series, it thins away rapidly to west and east." 

 The bone bed (Fd) "which we designate the Temeside 

 Bone Bed may be regarded as a grey micaceous grit, in 

 which large fragments of bone and fish spines are dis- 

 seminated. There is, in addition, a considerable amount 

 of carbonaceous matter, but whether of vegetable or animal 

 origin is not clear. As a whole, this Temeside Bone Bed 

 is coarser and more diffuse than the Ludlow Bone Bed, and 

 very different from the latter in general appearance." 



The succeeding olive shales {F,e) are 2 to 4 feet thick. 

 "Eurypterid remains are abundant," but hard to identify. 

 "These are succeeded by another grey micaceous grit, i foot, 

 (F,f ) at the top of which occurs a well marked layer crowd- 



