ON BRITISH MARINE ZOOLOGY. 247 
15 fathoms, and between that depth and 20 fathoms, we have the region of 
Nullipora. Below 20 fathoms, unless it be an occasional straggling Nullipora, 
no decided algz were met with. 
Traces of Vertebrata and land animals.—Had we no other evidence of the 
inhabitants of the sea than that afforded by the contents of the dredge, we 
might be tempted to infer a great rarity, almost amounting to an absence, of 
vertebrate marine animals within our area. Possibly such an inference 
would be quite as warrantable as the negative conclusions assumed from 
comparable observations by many paleontologists and geologists, who some- 
times go so far as to infer an entire absence of terrestrial creatures during 
some of the more ancient geological epochs, because no traces of them can 
be found in sedimentary strata of marine origin, and announce the laws 
which regulated the order of creation of animated beings accordingly. 
During the 145 detailed observations which form the bases of this Report, 
fishes were taken by the dredge not half-a-dozen times, and in three instances 
the fish taken was one of the rarest and most curious of British vertebrata, 
the Amphioxus lanceolatus. Although always carefully looked for and noted, 
the bones of fishes were never observed among the contents of the dredge 
above three times, and in two of those instances (at a depth of 40 and 50 
fathoms mud in the western coast of Scotland) the remains consisted of 
otolites only, reminding us of similar relics in the crag of the east of 
England. Of terrestrial vertebrata I have never seen a trace; and though 
no small number of the human race have diffused their bodies over our sea- 
bed, no human bone has occurred to me in dredging; when very near shore 
and in the immediate neighbourhood of a town, broken bottles and old shoes 
have strewn the sea-bed, affording unquestionable evidence of the presence of 
man on the neighbouring shores. Doubtless by dredging close to towns, in 
harbours and in estuaries, like the Mersey, where there are great cities on the 
banks, numerous relics of such a description, as well as the bones of animals, 
might be taken, but immediate proximity to towns is avoided by the dredger. 
On one occasion, recorded in the dredging papers from the Anglesey 
coast, the shell of a common snail (Helix aspersa) was dredged at some 
distance from shore in the entrance of the Menai Straits. It was covered 
by Balani and Serpule, and inhabited by a hermit crab. Naturalists 
familiar with the active movements of the Paguri, can readily conceive to 
what a distance a land shell may be transported under such circumstances, 
and at length become imbedded along with the remains of creatures of very 
different origin and habits. 
Fossil remains taken in the dredge.—In no instance have we taken the re- 
mains of fossil vertebrata when dredging on the western shores of Britain, 
but many times have met with fossil testacea. These are of the pleistocene 
epoch, and often it requires a practised eye to distinguish between them and 
the dead shells of existing mollusca associated with them; indeed there are 
some species, as Astarte crebricostata, Natica grenlandica, Panopea nor- 
vegica, Tellina proxima and Scalaria grenlandica enumerated in the pre- 
ceding pages, which, whilst from various considerations we hold the weight 
of evidence to be in favour of their presence as living species in our seas, are 
yet under suspicion, and are not admitted by all British conchologists. In 
several localities among the Hebrides, especially in the Kyles of Bute, and in 
sea between Raza and Applecross, quantities of pleistocene fossils may 
be dredged; at the former place, Panopea norvegica is common, as pointed 
ze by Mr. Smith ; and in the latter there occur numerous fossil valves of 
Ρ islandicus and danicus, the large sulcated variety of Saxicava rugosa, 
Astarte elliptica, Leda truncata and. oblonga, and very lately Leda thracia- 
