188 
PROFESSOR T. J. JEHU AND DR ROBERT CAMPBELL ON 
strands belonging to the clathria are the median, longitudinal strand and several 
lateral fragments seen on its left side ; those on the right are more obscure. The 
reticula is of much the same nature as that of Plegmatograptus nebula, but this 
graptolite has no well-developed clathria. Four thecal apertures are discernible, 
three close together on the extreme left, and one some little distance below them. 
The fact that none are seen on the right is probably due to the fact that the left 
side of the polypary is turned towards the observer, the right being turned away.” * 
Other specimens of graptolites were obtained later from the same exposure. 
These also were examined by Miss Elles, who reported that they belong to the 
family Diplograptidse, the genus being either Trigonograptus or Cryptograptus. 
Photographs of these specimens (magnified) are shown on Plate II, figs. 1 and 2. In 
the specimen represented by figs. 2a and 2b the outlines of the thecse can be 
Vehcula 
X a. 
Fig. 1. 
distinctly seen, and the position of the septum or axis is evident. A photograph of 
the counterpart of this specimen is also given (fig. 2). Owing to the oblique way 
in which the rock split the aspect of the polypary appears somewhat different. In 
the description of Cryptograptus given by Elles and Wood,| it is stated that the 
polypary varies much in appearance, according to the aspect from which it is seen. 
The specimens shown in figs. 1 and 1a are again counterparts. In these Miss 
Elles detected definite cells, which appear to show that the form is a Diplograptid 
— probably Cryptograptus. 
The genus Trigonograptus is recorded from the Upper Skiddaw Slates (Arenig) 
of the Lake District, and Cryptograptus ranges from the Middle Skiddaw Slates 
through the Ordovician System. 
III. BRACHIOPODA (see Plate I). 
The most numerous of the fossils which can be seen with the unaided eye are 
horny, hingeless brachiopods, often minute in size. The genera comprise Obolus, 
Geol. Mag., dec. vi, vol. i, p. 404, 1914, 
f Monog. Brit. Grap. (Pal. Soc.), vol. i, p. 295. 
