F. R. Cowper Reed — Evolution of Cheirurus. 161 



sandstones, which are red at Corrie, are respectively black and white 

 at Laggan : I submit that the redness is only a local peculiarity. 



Taking up the quotation at the point left off, Sir A. Geikie 

 writes (pp. 801, 828): "These fossils [i.e. the limestone fossils'] 

 are absent from the great series of red sandstones overlying the 

 limestone, and do not reappear till we reach the limestones in 

 the Lower Carboniferous series : yet the organisms must have been 

 living during all that long interval outside of the Upper Old Eed 

 Sandstone area." 



I admit that the limestone fossils are absent from the great series 

 of red sandstones ; but when Sir A. Geikie infers that these red 

 sandstones contain Old Red Sandstone fishes, I can but ask for the 

 production of even a single Old Eed Sandstone fish from any part 

 of the Island of Arran. That marine fossils should be " absent from 

 the great series of red sandstones overlying the limestone" was to 

 be expected, the fossils found in Carboniferous sandstones elsewhere 

 being exclusively plant-remains, and I am only aware of one bed 

 of sandstone in the West of Scotland containing marine remains, 

 and that is in the Upper Limestone series. 



Plant-remains are even commoner in Arran than I have seen them 

 elsewhere, a fact already sufficiently recorded by previous writers, 

 and which may be easily verified by anyone who walks along the 

 shore at Corrie, where they protrude every here and there from the 

 sandstone, while one sandstone intercalated between the limestones 

 in front of Corrie Hotel is packed with rootlets of plants. Plant- 

 remaius are also abundant all along the northern sections and also 

 towards the south in the cliffs of Maoldon. 



(To be continued.) 



v. woodwardian museum notes. 



Notes on the Evolution of the Genus Gheiruiw s . 

 By F. R. Cowper Reed, M.A., F.G.S. 



(Continued from the March Number, page 123.) 



ALONG the branch which is marked earlier by Cyrtometopus and 

 Cheirurus (sens, str.), the last stage of development corresponds 

 with Salter's subgenus Crotalocephalus. This is almost entirely 

 restricted to Devonian beds, but it is linked to Cheirurus (sens, str.) 

 in time and zoological characters by Ch. Sternbergi (Boeck) and 

 Ch. Quenstedti (Barr.), in which the glabellar side-furrows hardly meet 

 in the middle of the glabella. The important subgeneric characters of 

 Crotalocephalus are the continuous first and second side-furrows, the 

 triangular basal lobes which nearly or quite meet in the centre of 

 the glabella at their apices, and the nearly straight obliquely-directed 

 third side-furrows of the glabella. The earlier forms of the subgenus 

 have their triangular basal lobes still separated by a median portion 

 of the glabella, as in Ch. Quenstedti, from E'tage E. This species has 

 a rather curiously specialized kind of pygidium, with only two pairs 



DECADE IV. VOL. III. NO. IV. 11 



