Fossils of (he Potsdam Sandstone, 33 



formation ; and as most of the loose masses of stone which are to be seen 

 strewn about the surface of Canada have been transported from a greater or 

 less distant source, it is barely possible that they may belong to rocks of 

 some other age. 



2. Genus Lingula. 



The Lingular constitute a genus of small shell fish, several species of 

 which are living in the seas of the present day. Unlike the more com- 

 monly known tribes of animated nature, these now under consideration 

 have not the power of free locomotion, but are attached or anchored as it 

 were, by means of a slender flexible stalk, so contrived as to chain the 

 animal to one spot, on the bottom of the sea, throughout its life. Incon- 

 sistent as it may appear Avitli our general ideas of what a living creature 

 should be, with reference to its powers of motion, a very considerable 

 portion of the oceanic races are not free, but permanently fixed or grow 

 like a plant to the ground. Of the mollusca thus constituted, some have 

 one of their shells firmly cemented to the bottom, probably by means of an 

 exudation from the shell itself, which afterwards hardens — others by a 

 bundle of hair-like filaments, called a byssus, that issues from the interior 

 and becomes attached to a rock or floating piece of timber, while those of 

 a third tribe are provided with a short stalk, somewhat like that of a flower 

 in form and flexibility. The Lingulm are of the latter class. In the 

 collection of the Silurian Society at the City of Ottawa, there are two 

 specimens of the *' duck Lingula," Lingula anatina, lately procured from 

 the Indian seas, which have this stalk or pedicle, as it is called, preserved 

 and still attached to the shell. The largest of these specimens is 1| inch 

 in length, \ of an inch in breadth — of a light brownish colour, and in shape 

 somewhat like a duck's bill, whence its specific name. The pedicle issues 

 out from the interior, through the beak, or the part corresponding to the 

 smaller pointed extremity of the small fossils figured below. It is three 

 inches in length, and one quarter of an inch in breadth, semi-transparent, and in 

 appearance like a dried flat sinew from some quadruped. In its living state, 

 this pedicle is said to be cylindrical, and of the size of a small straw, but 

 flexible and contractile. It confines the animal to a circular space, upon 

 the bottom of the ocean, the diameter of which, in the case of Lingula 

 anatina is only about six inches. Within this limited domain, the duck 

 bill Lingula spends the w^hole of its life, subsisting upon such minute 

 articles of food as may be wafted by the currents, or otherwise brought 

 within its reach. Its diet consists most probably of the smallest animal- 

 cule or particles of vegetable matter difilised through the water. The 

 valves, or the two shells, open at the larger extremity, opposite the beak, 

 and while feeding there are protruded two slender flexible arms, fringed with 

 delicate hair-like filaments, called cirri, which, by constantly vibrating, 

 cause a current to flow in the direction of the mouth, situated within the 

 cavity formed by the two shells. The possession of those arms has 

 obtained for the class to which the genus Lingula belongs, the name of 

 3 



