Introduction. 



Since the publication of the first Part of this work I1903I three great and highly important 

 works on Echinoids have been published, viz. De Meijere: Die Echinoidea der Siboga-Expedition 

 (1904. Siboga-Expeditie. XLIII), A. Agassiz: The Pananric Deep-Sea Echini (1904. Mem. Mus. Comp. 

 Zool. XXXli and L. Doderlein: Die Echinoiden der dentschen Tiefsee-Expedition (1906. Deutsche 

 Tiefsee-Exped. 1898-99. Bd. V). De Meijere and Doderlein agree with me upon the whole in the 

 views on the classification of the regular Echinoids and on the systematic importance of pedicellariie 

 and spicules set forth by me in the first part of this work and in my work on the Echinoidea |I) of 

 the Danish Expedition to Siam 1899— 1900 (Mem. Acad. Roy. d. Sc. et d. Lettres de Danemark. 7. Ser. I. 

 1904). De Meijere only reserves his opinion as to my classification of the Cidarids, though recognizing 

 the importance of the differences in the structure of the pedicellariie made known by me; his objec- 

 tions that my diagnoses of the genera do not correspond with some of his new species and that my 

 classification leads to a great dismemberment of the system, I have replied to in my paper On some 

 Echinothurids from Japan and the Indian Ocean (Ann. Xat. Hist. Ser. 7. Vol. XIV. 1904. p. 91 — 92). 

 Doderlein after most careful and extensive researches states the general correctness of my views, 

 though, as might be expected from his somewhat better material, he has been able to improve the classi- 

 fication in several respects. Above all his results as regards the classification of the ( 'idarida are highly 

 important, and his arrangement of this family will doubtless prove correct, in any case for the very 

 largest part of it; upon the whole, I think, Doderlein is quite right in the several corrections of my 

 arrangement of genera and species of the regular Echinoids, though on this occasion I cannot enter 

 on a further discussion thereof. (I must, however, reserve my opinion as to Doderlein' s views of the 

 species of Sterechinus, till I have made reuewed studies on this group, which I intend to undertake 

 in the works on the Echinoidea of the German and the Swedish South Polar Expeditions). On this 

 occasion I can only express my admiration for the very clear and sound way in which Professor 

 Doderlein in his Introduction sets forth the signification of such structures as the pedicellarise in 

 the classification of Echinoids and meets the different objections which have been or might be made 

 against this use of them. 



In marked contrast to these two authors Professor A. Agassiz practically rejects all my results, 

 and expresses his contrary opinions in a way that seems to me not justified even by so great a renown 

 as his. The objections set forth by the famous author I do not find very strong, except as regards 

 the way in which they are expressed; but, of course, any criticism by so eminent an authority on the 

 Echinoidea demands a careful and detailed consideration. It was my intention to publish a reply to 

 the more personal criticisms of Professor Agassiz as a separate paper in some Periodical; but though 

 I might well be entitled to have published in some American Journal a defence against an unjust 





