52 Transactions. 
three feet square, sloping off east and west from a central ridge, 
saddle-like, is covered as closely and intricately as possible with 
designs of- a similar type to those shown on Pl. III., of which; 
indeed, it forms a portion. Several square feet to the east of 
this sculptured ‘‘saddle” are also very elaborately carved with 
what seein, at first glance, to be fresh designs, in which grooves 
straight and partly angular are more conspicuous than rings. 
There are also many small groupings of cups in threes and fives, 
some with grooves, others simple. The chief peculiarity in the 
portion shown in my diagram (Fig. 3, Pl. VII.) lies in the whole 
inner surface of the ring marked A being hollowed out to a level 
below the actual level of the surrounding rock. This ring is ten 
inches wide, and the adjoining circle eleven inches. 
Ill. The Graptolites of the Moffat District. 
By Mr James Darron, F.G.S. 
It may be remembered that the specimens which I exhibited 
before this Society on the last occasion were, with few exceptions, 
principally the simpler forms belonging to the genera Monograptus 
and Diplograptus. To-night, I shall bring forward a few of the 
more complex kinds, also found in the lower Silurian or upper 
Llandeilo rocks of the south of Scotland from the locality of 
Moffat. Although these ancient Zoophytes have not a wide 
range in the earth’s crust, being exclusively confined to the 
Silurian system, yet, geographically speaking, they are found in 
various countries of the globe, indeed wherever these rocks exist. 
I shall again briefly describe their structure, and with the assist- 
ance of this model, the accompanying drawings, and specimens 
which are on the table, those of you who are unfamiliar with the 
subject will, I trust, be able to follow me as I proceed in the 
enumeration of the different species. . 
We shall now notice Monograptus Sedgwickii.—There is no 
Graptolite, it may be stated, that assumes so many different forms 
and variations of form as this species. Many of these differences, 
I have no doubt, may arise from their state of preservation, their 
age, or their sex. There are two or three varieties, which appear 
to be distinct enough to be entitled to distinct names. The 
general form of I. Sedgwickii, as described by Portlock and 
figured by M‘Coy, consists of a simple Monoprionidian stipe of 
