THE EEVISION OF THE ECHINI 119 



But I will not bother you with more remarks on this 

 head. 



Pray give my most sincere respects to your father. 

 What a wonderful man he is to think of going round 

 Cape Horn ; if he does go, I wish he could go through 

 the Strait of Magellan. 



With very kind remembrances from all of us to Mrs. 

 Agassiz, and with many thanks from myself, 

 Pray believe me, 



Yours very sincerely, 



Ch. Darwin. 



Professor Agassiz sailed in the Hassler for a dredging 

 expedition around South America in December,' 1871. 

 This time during his absence the work of the Museum 

 management did not all fall on Agassiz's shoulders, for 

 Mr. Thomas G. Cary, the brother-in-law of the elder 

 Agassiz, had charge of the finances. 



TO DARWIN 



Cambridge, March 4, 1872. 

 Many thanks for the copy of the new edition of the 

 "Origin of Species," which I have just received from 

 you. There are several points, especially in Embryology, 

 which I shall take some other occasion to write you 

 about, which may be of general interest. I am getting 

 on toward the end of the Report on Echini from the 

 deep sea of Florida, and hope to be able to send 

 you a copy before long. The number of young I have 

 been compelled to examine has led me to modify my 

 views of the nature of genera, species, and in fact of 

 all subdivisions. I cannot find anything that is stable, 

 the greater the material in space and number (age) the 



