Figures and Descriptions of Canadian Organic Remains. 301 



technical descriptions of the species. But being intended also for 

 the use of the students of Canadian geology — whose number is 

 rapidly increasing throughout the Province — it appears necessary 

 to commence with a general summary of what has been ascertained 

 up to the present time concerning the zoological characters and dis- 

 tribution in time and space of this somewhat extraordinary group 

 of extinct organisms. By this course it is hoped that, while the 

 foreign geologists will leceiveall the intimation he desires of what 

 we are doing, the growth of science in our own country will also 

 be promoted. 



" The Cystidese were a race of small marine animals, which 

 flourished vigorously during the Silurian period, but totally disap- 

 peared before the commencement of the Carboniferous era. They 

 were closely allied to that interesting family, the lily encrinites, 

 or Crenoids, and, like them, entirely covered, as with a coat of mail, 

 by a dermal or external skeleton of thin calcareous plates, which 

 were sometimes richly ornamented with radiating ridges or striae. 

 Attached to the lower extremity of the body was a short flexible 

 stalk, usually called the column, that served to anchor the animal 

 securely to one spot on the bottom of the ocean throughout life ; 

 and at the opposite, or upper end, a set of arms, which, in addi- 

 tion to their other functions, may have assisted in the collection of 

 food by exciting currents of water towards the mouth. This latter 

 organ was a circular or oval aperture, situated in the side, below 

 or near the summit, and in some species must have been also the 

 passage through which such matter as could not be digested was 

 thrown out. The young were developed from eggs, which were, 

 there is good reason to believe, generated in the grooves of the 

 arms, or pinnulse, where, as has been ascertained by actual obser- 

 vation, the organs of reproduction are situated in the Crinoids that 

 exist in some of the seas of the present time. 



" Concerning the food, habits, or other particulars of the natural 

 history of the Cystidese, we can never hope to acquire any great 

 amount of information, as the race wholly perished many ages ago 

 and the only evidences we have of its existence are, with few 

 exceptions, very imperfect skeletons, which exhibit nothing except 

 the structure of the external hard parts. It is only probable that 

 their nourishment was derived from minute particles of animal or 

 vegetable matter diffused through the waters in which they lived. 

 The structure and position of the mouth are such, that they could 

 not have been highly carnivorous, while their nearly sedentary 



