Baily — Cambrian Rocks and Fossils. 399 
worm, evidently cephalo-branchiate, and not very dissimilar from 
the common Lug-worm (Arenicola) of our present seas. 
The same author also collected and described * what he believed 
to be another addition to the Cambrian fauna, under the name of 
Haughtonia pecila, but in which, as he states, ‘the organic character 
is not so evident or satisfactory:’ he supposes it to be the ‘ traces of 
an ageregation of tubes constructed by gregarious tubicolous worms 
belonging to the Annelida, and allied to Sabella.’ It was found by 
him on the upper surface of a coarse reddish grit near the ‘ Peri- 
winkle Rocks’ of Bray Head, and shows a peculiar and regularly 
mottled appearance ; what he supposes to be the tubes are white, and 
the interspaces red, and a vertical section exhibits a series of these 
tubes filled up with sand. The author, in acknowledging the diffi- 
culty of establishing the claims of such mere traces to be considered 
as fossils, expresses himself as follows,—upon ‘the importance of re- 
cording every organic trace which tends to throw a light on the 
habits of the animals which lived at so early a period of the world’s 
history as the Cambrian ;’ an observation with which I fully concur : 
at the same time, I must confess, I do not consider the specimen 
sufficiently definite, as to its organic nature, to warrant its receiving 
a name or being included amongst the fossils of the Cambrian 
formation. 
In concluding these remarks, which are merely intended as a 
sketch of all that is at present known respecting the value of the fossil- 
evidence derived from the large masses of stratified rocks known in 
the British Islands as the Cambrian formation, it will have been 
seen that the only reliable proof of the remains of organic life is fur- 
nished by strata, referred to this series, in Shropshire and the South- 
east of Ireland; the former yielding merely tracks and burrows of 
marine animals, probably Annelids; the latter, a more varied and 
important assemblage, consisting of those well-marked and charac- 
teristic forms of Oldhamia believed to be the remains of zoophytic 
animals, and similar Tracks and Burrows to those found in the rocks 
of the Longmynds, with the addition of a large tubeform cast called 
EMistioderma, resembling that of an Anneloid worm. 
Some of the finer grits and more argillaceous beds, like those of 
the Longmynds, often display ridged and wrinkled surfaces, such as 
may be seen on the sea-shore at the present day, and which were pro- 
bably due to the same causes, namely, the quiet action of the advan- 
cing or receding wave, or the agitation of the water by wind over a 
shallow shore. 
From these results of the labours of investigators as to the Fossils 
of the Cambrian Rocks, we get tangible evidence of the existence of 
marine forms of life bearing a considerable resemblance to those of 
the present day, although the variety we are at present acquainted 
with is small. There may, possibly, as suggested by other writers, 
have been a more varied assemblage, including marine plants, and 
some of the softer kinds of Zoophytes, Mollusca, or other Invertebrate 
* Journ. Geol. Soc. Dublin, vol. yi. p. 116. 
