196 NEW YORK STATE MUSEUM 



more varied points of view and the remains of forms that per- 

 ished ages ago must, in an exceedingly large measure, be in- 

 cluded in the reckoning. With such a phylogeny established, 

 the study of ancestral types having living descendants is not a 

 very difficult matter. If, however, the fossil forms are not an- 

 cestral but are highly specialized types that left no descendants 

 it is the morphology of the nearest related ancestral types that must 

 receive more extensive and intensive study, if we are to under- 

 stand the modification of such structures as are now presented. 

 There is no short road from ahy living echinoderm across to the 

 Blastids of the Carbonic era, but the true roads run from the 

 Echinoderm of the present to Cambric or Precambric times and 

 from that remote station, by a branch line, to our desired 

 destination. 



So much by the way of preface has seemed necessary to give 

 the author's point of view in the present paper. He is at present 

 quite content to reach a Precambric station in Echinoderm terri- 

 tory by any modern line and hypothetically accept a hypothetical 

 primitive Echinoderm as our best modern students have seen 

 him. From this Precambric station, guided by well-established 

 physical principles, he will reach out into the region of the little 

 known and try to discuss helpfully some curious and interesting 

 structures presented by the relics of a few ancient beings who 

 lost consciousness in Chazy time. The author reserves the 

 right to use any evidence which the morphology of living things 

 may present; he feels that in this remote field the best of present 

 guides may lead him to draw erroneous conclusions, but he 

 sincerely hopes that after the paper has passed the fire of con- 

 temporary criticism there will still be left some small measure 

 of fact that may help toward a better understanding of the 

 obscure forms in question. 



Echinoderm respiration. Anything tending to interfere with 

 the function of respiration would inevitably lead to greater res- 

 piratory effort. If more than one organ or structure shared in 

 the respiratory process, as they do in all Echinoderms, inter- 

 ference with one structure or set of structures would mean in- 

 creased effort for others, that the physiological balance might 

 be maintained. Prolonged effort would mean abnormal develop- 

 ment. The earlier this interference appeared in the life of the 

 individual the more profound would be the modification pro- 

 duced. The ability to modify structure varies with the indi- 

 vidual. Variation in direction and degree of such variability 



