Baily— Cambrian Rocks and Fossils. 397. 
dent, both of these species or varieties being abundant at the present 
day on the same (east) coast of Ireland. To the former—S. cupressina 
—it is said by Professor Forbes to present a striking resemblance, 
whilst Dr. Kinahan considers its nearest comparison to be with S. 
argentea: either of which conclusions may be correct, when we con- 
sider the probability of their being merely varieties of one species ; 
a question upon which Dr. Johnston makes the following remark : 
‘ Pallas thinks they constitute but one species, his cupressina.’ * 
No comparison having hitherto been made known between Oldhamia 
radiata and any living forms, I have endeavoured to trace out its 
nearest alliance, in accordance with the views of Professor Forbes, 
as to the probability of its being related to the Sertulariade, and 
find this species bears a considerable resemblance to some of the 
frondose or bushy examples of that family, particularly to Cellularia 
plumosa, which is said’ by Dr. Johnston ‘in habit to be something 
like S. argentea’ (a species previously alluded to as comparable with 
O. antiqua): the fossil is, however, more tufted and bushy, although 
not very unlike in form what we may suppose such a recent species 
would assume if spread out and subjected to pressure, as these 
fossils must have been. 
With reference to the remark made by Dr. Kinahan, ‘that it is 
questionable whether it would not be more convenient to place these 
two kinds of Oldhamia under separate genera,’ + I would observe 
that, in the absence of any satisfactory evidence as to the presence 
of reproductive organs, we can,I think, only consider them as being 
specifically and not generically distinct ; for although differing in the 
mode of arrangement of their parts, they appear to be sufficiently alike 
in general character to justify our retaining them under the same 
generic appellation. The specific distinction is also supported by the 
difference in the condition of the deposit in which the two kinds occur; 
O. antiqua being most frequently met with in the softer or shaly 
beds, whilst O. radiata is abundant in the more compact and gritty 
beds, the two species, as before observed, being seldom if ever found 
together. 
Accompanying the Oldhamia, at all the localities mentioned, are 
unmistakeable evidences of other marine animal life, in the nume- 
rous tracks and burrows often found intermixed with them in 
the same beds, and sometimes occurring in distinct ones in their 
immediate neighbourhood. 
These tracks are of various forms and sizes; some of them nearly 
straight, some slightly curved, and others more or less tortuous, 
resembling very much those produced by sea-worms belonging to 
the Annelida on sandy shores at the present day. Some of them 
occur in pairs of double openings, the tubes from which pass verti- 
cally through the beds; they appear to be identical with those from 
the Longmynds described by Mr. Salter, and named by him Areni- 
colites didyma. These double orifices, fig. 4, 6, are seen to be inter- 
* British Zoophytes, vol. i. p. 341, and pl. 16, fig. 1. 
{ Treatise on Oldhamia, p. 551. 
