166 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



later Doderlein (:06), x in an effort to avoid some of the difficulties of 

 Mortensen's system, and yet to retain the valuable results of his work, 

 offers a classification of the recent Cidaridae, consisting of ten genera and 

 five subgenera, defined chiefly in terms of the pedicellariae. This classi- 

 fication, however, is quite different from any of its predecessors because, 

 while Doderlein attempts to apply rigidly the recent International Code 

 of zoological nomenclature, his interpretation of certain perplexing cases 

 is quite different from either Mortensen's or Agassiz's. Finally Agassiz 

 and Clark ( : 07) 2 reject the proposed innovations of both Mortensen 

 and Doderlein and offer considerable evidence in support of their view 

 that the pedicellariae of the Cidaridae are as unreliable for generic char- 

 acters as are the spines. 



It is perfectly obvious, therefore, that the classification of the Cidaridae 

 is at the present time in a state of great confusion, and that some effort 

 should be made to reduce it to order and place it on a permanent basis. 

 Thanks to the great kindness of Mr. Agassiz, a very unusual amount of 

 material, both recent and fossil, has been accessible to me during the past 

 two years, and I have endeavored to find and formulate a natural arrange- 

 ment of the Cidaridae. Needless to say, Mr. Agassiz is not responsible 

 in any way for statements made or opinions expressed in the following 

 pages, but whatever value my results may have are due to his constant 

 sympathy and encouragement, and I wish here, in this inadequate way, 

 to express my thanks to him. I have also to thank Dr. Richard Rath- 

 bun for the privilege of examining the collection of Cidaridae in the 

 United States National Museum, and this proved to be of added interest 

 because it has recently been studied by Dr. Mortensen, who, in many 

 cases, left labels in his own hand, showing the views he held as to the 

 identification of the specimens. As my point of view differs fundamen- 

 tally from his, I desire to do him full justice, and the examination of a 

 collection, a large part of which has been named by him, was therefore 

 of special importance to me. Finally I may add that in the prepara- 

 tion of this report I have personally handled not less than 3,100 speci- 

 mens, representing 48 of the 60 recent species which appear to me to be 

 valid, and all of the 1 5 recent genera herein recognized. 



1 Die Echinoiden der deutschen Tiefsee-Expedition. Ludwig Doderlein. 290 pp., 

 42 pis. Jena, 1906. 



2 Hawaiian and other Pacific Echini. The Cidaridae. Alexander Agassiz and 

 Hubert Lyman Clark. Mem. Mus. Comp. Zool., 34, 42 pp., 44 pis. 1907. 



