in the Gulf of St. Lawrence. 353 



it is composed are remarkable alike for their geological anti- 

 quity and for their wide range of geographical distribution. 

 In time, a few of them date back to as ancient periods as the 

 Coralline and Red Crags, and a much larger number occur in 

 the Postpliocene deposits of both Europe and North America. 

 It is curious to observe that species which are found both living 

 on the American coast to-day and fossil in the European 

 Pliocene and Postpliocene, had a different geographical range 

 in former times from that which they are known to have now. 

 Many of these arctic marine invertebrates are circumpolar in 

 their distribution, and not only inhabit both sides of the At- 

 lantic, but are also found in the Northern Pacific. The prece- 

 ding generalizations refer almost exclusively to the assemblage 

 of marine animals characteristic of comparatively shallow 

 water, the members of which range in depth from low-water 

 mark up to about 50 fathoms. 



The deep-water fauna, at least that of the localities examined, 

 is also decidedly arctic, but it has at the same time a much 

 more Scandinavian aspect. Nearly all of the species which 

 are now for the first time recorded as inhabitants of the Atlantic 

 coast of America occur also in the seas of the north of Scot- 

 land, of Norway, and Spitzbergen. There is a striking simi- 

 larity between the series of fossils from the Quaternary deposits 

 of Norway (as catalogued by Sars) and the marine inverte- 

 brates of the deepest parts of the St. Lawrence. Pennatuke, 

 Ctenodtscus, Trijyi/lus [ScMzaster)ffagiUsj Ophioglypha Sarsii, 

 together with many species of mollusks, are common to both. 

 Still it must be borne in mind that in the Quaternary deposits 

 of Norway a number of characteristic European invertebrates 

 occur, which, so far as we know, do not live on the western 

 side of the Atlantic. 



In the River and Gulf of St. Lawrence, generally speaking, 

 the number of species of marine animals which may be collected 

 at or above low-water mark is very small ; few specimens, 

 apparently, are washed ashore by storms. But there is a con- 

 stant tendency in the opposite direction ; littoral and shallow- 

 water forms are constantly being drifted down to lower levels, 

 particularly shells (which are usually dead and empty) and the 

 larger calcareous Polyzoa, such as Celleporaria incrassata and 

 Myriozoum suhgracile. Sometimes the Mollusca are living : 

 on one occasion I dredged an example of Littorina rudis^ 

 apparently alive, but certainly with the operculum fitting 

 tightly into the apertui-e, from upwards of 100 fathoms water. 

 When such is the case, it is often difficult to separate the true 

 denizens of the deep sea from those which are washed down 

 from shallower water. 



