242 Proceedings of the Royal Physical Society. 
fossil. From a basal stalk-like portion several branches are 
given off (which probably originate through dichotomy of 
the stalk-like pedicel). These branches, by repeated 
dichotomy, form a frondose expansion, consisting of a series 
of equal dichotomies. . 
Fig. 1 shows the upper part of a similar specimen, 
where the same characteristic dichotomy of the branches is 
well exhibited. Neither of these specimens gives in any 
case a well-preserved termination of the branchlets, but this 
point is well illustrated by the small specimen given at 
Fig. 2, and the termination of the branches is represented 
enlarged at Fig. 2a. Their apices are blunt and slightly 
swollen. 
There is no data from which the affinities of these fossils 
can be discussed. The species has been named from the 
locality at which it was discovered. 
My thanks are due to Sir Archibald Geikie for kindly 
giving me the opportunity of figuring and describing the 
specimens. 
The fossils were collected by Mr James Rhodes, one of 
the Fossil Collectors to the Geological Survey of England, 
and are in the Geological Survey Collection, Museum 
of Practical Geology, Jermyn Street, London. 
Locality.—W orston Beck, near Clitheroe, about a quarter 
of a mile above Hall Foot House, Lancashire. 
Horizon. — Shales under Pendleside Limestone, Car- 
boniferous Limestone Series of England (=Calciferous 
Sandstone Series of Scotland), 
EXPLANATION OF PLATE. 
Figs. 1-3. Bythotrephis Worstonensis, Kidston; natural size. 
Fig. 2a. Small portion enlarged to show the terminations of the branchlets. 
Registration numbers of specimens in the Geological Collection,—Fig. 1, 
No. Rh. 975; Fig. 2, Rh. 975; Fig. 3, Rh. 979. 
