84 CALAMOCEINUS DIOMED^. 



On some of the Homologies of Echinoderms. 



I have not found it possible to discuss in the later of my publications on 

 Echinoderms,* limited mainly to systematic work, many interesting points 

 on their homologies which have been suggested by writers on Echino- 

 derm morphology since the publication of my memoirs on the Etnbryology 

 of Echinoderms in 1864. Owing to the republication of the greater part 

 of one of these papers in 1874,t and of the other in 1877,:}: recent 

 writers quote them as dating from the reprints, which thus appear as 

 following the lead of naturalists whose results were published from five to 

 seven years later. I mention this, not for the purpose of making any 

 reclamation for the sake of priority, but to account for the anachronisms 

 and contradictory assertions and opinions which have been attributed to 

 me by writers who have either never seen the original memoirs I re- 

 fer to, or who have not chosen to remember that their reprints repre- 

 sented work published thirteen years earlier. To those naturalists Avho 

 deem it necessary that any criticism of their views should at once be no- 

 ticed, I may seem to have acquiesced in the justice of their criticisms. 

 It is one thing to meet new views with new observations ; but merely 

 to write an essay on an old subject for the sake of defending one's 

 position has never seemed to me worth while. It does not particularly 

 interest those who are not specialists in any branch that the views of 

 A, B, or C should be quoted as frequently as they become modified in the 

 pages of the next periodical to appear. To follow the researches of our 

 fellow workers is a most grateful task ; but no investigator should be ex- 

 pected to keep up with the daily vagaries, impressions, and endless changes 

 of front which must necessarily accompany any extended investigation, 

 if they are to be published one day only to be contradicted the next. 



The greatest caution should be exercised in carrying out the homolo- 

 gies of the different classes of Echinoderms into the minor details of the 

 plates of the abactinal system. From the time of the Silurian we have 

 had fossil Starfishes and Ophiurans differing but slightly from their con- 

 geners of the present day, and the development of the Crinoid, Starfish, 

 and Ophiuran has been going on simultaneously from the earliest times, 

 with but few of the so called transition forms belonging to the oldest 



« Revision of the Echini, 1874 ; Challenger Echini, 1881 ; Blake Echini, 1883. 

 t Revision of the Echini. J North American Starfishes. 



