3IO Dwellers of the Sea and Shore 



or in baroque contorted shapes. Some were of gigantic 

 size, one species probably weighing several tons, and 

 lengths of five or more feet were not uncommon. Of 

 the ammonites more than 5,000 species are known, but 

 all disappeared from the ocean during the Cretaceous 

 period; that is to say, while the chalk cliffs of England 

 were still beneath the sea. The nautilus race declined 

 more slowly, until to-day we find less than a half dozen 

 species making their last stand in the depths of the 

 tropical Pacific. Contrary to popular belief, they do 

 not swim at the surface, but live near the bottom at a 

 depth of about 1,000 feet — seldom are they found in 

 water of less than 100 feet. To the inexpert eye the 

 shells of ammonites and nautili might easily be mis- 

 taken for one another, but there is a difference in the 

 partitions that separate the chambers, and the shells of 

 ammonites are usually more ornamented exteriorly 

 with ridges and projections. 



Just about the time the stage was set for the moUusks 

 to appear, however, another creature called the brachi- 

 opod, had also established itself. And here, by the 

 way, is something curious. The brachiopod, although 

 not a moUusk, looks, superficially at least, strangely like 

 one. Considering the popular conception of mollusks, 

 I might go further and say that the brachiopod looks 

 more like a moUusk than do many of those animals 

 themselves. There are a few living representatives of 

 this ancient animal, and they are very much like the 

 ancestral type in appearance, being little changed in 

 that long stretch of time since they left their dead shells 

 just off the shores of the Cambrian seas. They live 

 below the low-water mark, usually in depths of 100 feet 



