140 THE ROYAL SOCIETY OF CANADA 



as the Thormanby islands on the east side and the Winchelsea islands 

 on the west side. The nearest known rookery is on the Jagged islets, 

 21 miles south of Cape Flattery off the Washington coast and this 

 must be at least 160 miles away. As no very large or very small ones 

 are seen, it may be that these are the immature males and females, 

 while mature individuals as well as pups of the year do not get so far 

 away. It is quite possible that these immature individuals do not 

 remain at the rookery during the pupping season. On July 9, 1916, 

 two sea-lions were seen on Butterworth rocks, to the northwest of 

 Stephens island, near Prince Rupert. This was in the pupping season 

 and yet Butterworth rocks are 150 miles from the nearest known 

 rookery. It is probable that these were immature individuals. If 

 that is the case the migratory habit is not so strong in the sea-lions as 

 in the fur seals. 



Apart from the vertebrates, the ascidians are the only chordates 

 well represented and as these are sessile they do 'not come under 

 consideration. 



In the Mollusca, the different classes behave so differently that 

 they must be taken separately. Among the Pelecypods, some, like 

 the oyster, are sessile, others like the mussel, are attached by a byssus 

 or like the rock oyster (Anoniia), with a byssus plug or muscle. Nearly 

 all those that are not definitely attached, are so sedentary, that as far 

 as migration is concerned they might as well be. Even the razor clam, 

 with greater rapidity of movement than the others, can scarcely be 

 classed among the wanderers. The adults of the whole class then 

 may be considered as non-migratory. The species of Amphineura are 

 sluggish also but they are more mobile in general than the bivalves. 

 In one species at least there is evidence of migration. The large 

 Cryptochiton, in the vicinity of Nanaimo, may be found high up on 

 the rocks, much above low tide, in the early spring, but later in the 

 year it is found only in deeper water. A few fathoms may not seem 

 much of a migration, but it is relatively as much to the slowly creeping 

 chiton as many miles would be to the rapidly swimming seal or salmon. 

 In the Gastropods, as an example of a migratory shelled form, there is 

 the common moon shell or large whelk {Polynices lewisii). During 

 the early part of the summer it burrows in the sand or mud in the 

 tide flats, sometimes much above low water mark. In July or there- 

 abouts, the eggs are laid, stuck together with sand to form the large 

 sand collars and shortly after they all go out to deeper water, and 

 none can be found at their earlier haunts. The nudibranch species, 

 Chiorœra leonina, appears in great numbers on the eelgrass just 

 below low tide during the late winter and early spring months. In 

 March the frill of eggs are laid on the eelgrass and soon after the ani- 



