SEA-LILIES AND FEATHER-STARS 



By AUSTIN H. CLARK 



(With i6 Plates) 



CONTENTS p^^E 



Preface i 



Number and systematic arrangement of the recent crinoids 2 



The interrelationships of the crinoid species 3 



Form and structure of the crinoids 4 



Viviparous crinoids, and sexual differentiation lo 



The development of the comatulids lo 



Regeneration 12 



Asymmetry 13 



The composition of the crinoid skeleton 15 



The distribution of the crinoids 15 



The paleontological history of the living crinoids 16 



The fossil representatives of the recent crinoid genera 17 



The course taken by specialization among the crinoids 18 



The occurrence of littoral crinoids 18 



The relation of crinoids to temperature 20 



Food 22 



Locomotion 23 



Color 24 



The similarity between crinoids and plants 29 



Parasites and commensals 34 



Commensalism of the crinoids 39 



Economic value of the living crinoids 39 



Explanation of plates 40 



PREFACE 

 Of all the animals living in the sea none have aroused more general 

 interest than the sea-lilies and the feather-stars, the modern repre- 

 sentatives of the Crinoidea. Their delicate, distinctive and beautiful 

 form, their rarity in collections, and the abundance of similar types 

 as fossils in the rocks combined to set the recent crinoids quite apart 

 from the other creatures of the sea and to cause them to be generally 

 regarded as among the greatest curiosities of the animal kingdom. 

 They have usually been considered as the rare, curious and decadent 

 remnants of an interesting animal type once important but now 

 trembling on the verge of extinction, and it is from this melancholy 

 viewpoint that they are discussed in practically all the text-books. 



Smithsonian Miscellaneous Collections, Vol. 72, No. 7 



