PREFACE 



Mrs. H. L. Clark and her family have done me the great honour of 

 asking me to edit my late friend H. L. Clark's Report on the Echini of 

 the Warmer Eastern Pacific collected by the Velero III. In so doing I 

 have thought it a holy duty towards my dear colleague and friend through- 

 out nearly half a century to let his report appear in the main as it was 

 intended by him, adding only some few remarks here and there, which I 

 have deemed necessary. Only in his dealing with the genus Encope a more 

 serious correction has been introduced. It was the idea of Clark that the 

 genus ought to be divided in two separate genera, the species grandis to 

 form a genus of its own in contradistinction to all the other species. This 

 is in my opinion quite unacceptable. The only difference is that grandis is 

 thicker and somewhat heavier than the other species ; but whether the edge 

 of the test is 5 mm or only 2-3 mm thick is certainly not a morphological 

 difference of generic value, and there are no other differences ; especially it 

 should be emphasized that the internal structure of the test is exactly the 

 same as in the other species. Moreover, separating grandis as a distmct 

 genus from all the other species would necessitate most regrettable nomen- 

 clatorial changes. His idea that the species emarginata would be the geno- 

 type of Encope is decidedly erroneous. When establishing the genus 

 Encope L. Agassiz (1840) named only a single species, grandis; accord- 

 ingly grandis is the genotype of Encope. In one of his last letters to me 

 Clark said that he would abide at the decision which I would make in this 

 question. I wrote him at once that there could be no question at all but 

 that grandis is the genotype of Encope, and he would certainly have 

 changed his manuscript in accordance herewith; but he did not get the 

 time to do so. I have thus had to change that part of his manuscript. 



As for the numerous new species of Encope which he establishes I think 

 he is going much too far, small individual or local variations of this pro- 

 lific genus being taken to represent distinct species. A few specimens (one 

 of each species, and some of them too young to be of any use) sent me by 

 Professor McCulloch do not at all convince me of the value of all his 

 species; but without having access to the rich material on which Clark 

 based his various species it is impossible for me to decide which of his 

 Encope species are of real value and which are not. I deem it therefore 

 our duty to publish them all, as Clark meant to have it done. It must then 



XI 



