THE SPONGES. 10 



sincere thanks. To the trustees and to President Gihnan of the Carnegie 

 Institution I wish also to express my hearty thanks for a generous grant 

 which enabled me to carry out my plans. My year was spent chiefly in 

 Berlin, in the laboratory of Geheimrath F. E. Schulze, although visits were 

 made to the museums in London, Paris, and Leyden. To Geheimrath 

 Schulze I am under lasting obligation, not only for the permission to 

 occupy a working place in his Institut, but for the generosity with which 

 he allowed me to make use of his library, photographic atelier, and 

 collections, in particular his magnificent collection of microscopical prepa- 

 rations of the Hexactinellida, and finally for the helpful suggestions and 

 friendly aid with which he responded to all of my calls for assistance. 

 To another friend in Berlin, Professor Wilhelm Weltner, Gustos in the 

 Museum fur Naturkunde, I am likewise under deep obligations for assist- 

 ance in the use of the admirable collections of the Museum, and for aid 

 of many kinds. To Geheimrath K. Mobius, Direktor of the Museum flir 

 Naturkunde, I offer my respectful thanks for the use of the photographic 

 atelier, and for the kindly permission to make free use of the library 

 and collections in the Museum. My respectful thanks are also due to 

 Geheimrath E. von Martens of the Museum fiir Naturkunde for facilities 

 allowed me during the course of my work in the Museum. 



To the following gentlemen also I beg leave to express ray thanks : 

 to Professor E. Ray Lankester, Director of the British Museum (Natural 

 History), for permission to examine types, and to Professor T. Jeffrey Bell 

 and especially to the curator of sponges, Mr. R. Kirkpatrick, of the same 

 Museum, for courtesies shown me during my visit; to Professor Edmond 

 Perrier, Director of the Museum d'Histoire Naturelle, for permission to 

 examine the collections, and to Professor E. L. Bouvier of the Museum for 

 courtesies shown me during my visit ; to Professor E. A. Jentink, Director 

 of the Rijks Museum in Leyden, for permission to examine types, and to 

 Dr. R. Horst of the same Museum for courtesies shown me during my visit. 



Finally I desire to thank Mr. Agassiz not only for the opportunity of 

 studying the valuable collection upon which I now report, but for the 

 patience with which he has waited for the report. 



University op North Carolina, 

 Chapel Hill, N. C. 

 Jan. 22, 190i. 



