In many, if not in most, groups, as in the ophiuroids, 

 the adults, at least of most of the species, are bottom living, 

 but the young are pelagic and rise toward, or even to, the 

 surface in order to undergo development, sinking again when 

 the adult form is attained. It is evident, therefore, that such 

 animals, though living as adults in deep water, are distributed 

 entirely by the surface currents. 



The crinoids, from the nature of their development, are 

 distributed very slowly, and such distribution as they attain 

 must of necessity be the result of a circular dispersal or 

 scattering of the young from each parent if there are no 

 currents where they exist, or the result of the motion of the 

 water by ivhich they are immediately surrounded. The crinoids 

 cannot become dispersed through the action of the currents 

 in the higher water levels above them in the way common 

 to most of the other bottom inhabiting marine types. 



The fundamental difference in the factors governing the 

 dispersal of the ophiuroids, echinoids and asteroids on the 

 one hand, and the crinoids on the other, was strikingly brought 

 to my attention in the course of my work in the north Pacific ; 

 for it was no uncommon occurrence to find in the same dredge 

 haul typical Magellanic crinoids (brought from the south by 

 the deep currents) mixed with typical arctic ophiuroids, 

 echinoids and asteroids (the larvae of which had been brought 

 from the north by surface currents flowing high above the 

 habitat of the adults). 



The Range of the Genus Feorometra. 



The distribution of the species of the genus Floromeira (i) 

 offers an interesting problem in zoogeography and, considered 



(i) The type of this genus is Antedon mariœ A. H. Clark, 1907, from 

 southern Japan. Properly speaking the genus is only a subgenus of 

 Promachocrinus, which I consider as including the subgenera Proma- 

 chocrinus, sensu stricto [Promachocrinus kerguelensis P. H. Carpenter), 

 Solanometra (Antedon antarctica P. H. Carpenter), Anthometra [Antedon 

 adriani Bell), and Florometra [Antedon asperrima A. H. Clark, Antedon 

 hondoensis A. H. Clark, Antedon inexpectata A. H. Clark, Antedon laodice 

 A. H. Clark, Antedon magellanica Bell, Antedon mariœ A. H. Clark, 

 Antedon perplexa A. H. Clark, Antedon rathbuni A. H. Clark, Antedon 

 serratissima A. H. Clark, and Antedon tanneri Hartlaub). 



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