XVIII. Revision of the North American Poeiferje ; wiTn Remarks 

 upox Foreign Species. Part II. 



By Alpheus Hyatt. 



Read April 5, 1876.' 



OINCE these Memoirs were begun, my views with regard to the affinities of the 

 Sponges have changed completely, so that instead of regarding them as a class of Infu- 

 soria, I now look upon them as a distinct sub-kingdom or branch of animals, equivalent 

 structurally to the Vertebrata, or any of the larger divisions which are characterized by 

 the most important structural differences. The plan of these Memoirs does not permit me 

 to discuss this question at present, nor is it requisite, since I have already published two 

 papers bearing on this point, one jirepared some months since for Johnston's American 

 Encyclopedia, which will shortly appear, and one in the Proceedings of the Boston Society 

 of Natural History for November, 1876. 



In addition to the acknowledgments for assistance rendered by various institutions and 

 individuals in the First Pai't of this Memoir, I have now most gratefully to add the follow- 

 ing names. Prof. Baird, as Director of the National Museum, placed a fine collection of 

 commercial "sorts" in my hands for identification. Dr. W. G. Farlow presented to the 

 'Boston Society of Natural History a fine collection, made on the south coast of Australia. 

 The Academy of Natural Sciences of Philadelphia, loaned me their valuable collection 

 of Keratose sponges. Mr. Gurdon Saltonstall made numerous inquiries with regard to 

 the influence of physical agencies upon the West Indian Spongise at Nassau, and con- 

 tributed thereby information having a very impoi'tant bearing upon the questions dis- 

 cussed in the following pages. Mr. Geo. Brown Goode of Wesleyan College, Middletown, 

 who is now collecting at Bermuda, has furnished me with information of general import- 

 ance, and I am also indebted to him for a complete suite of the Spongite of that locality 

 selected so as to show the varieties. Dr. E. Ehlers of Gottingen, in the most generous 

 manner, forwarded his preparations of the skeletons of the original specimens in Esper's 

 collection, which have been invaluable for comparison. The Messrs. Isaacs of New York 

 gave me every fiicility for the examination of their large warehouse-stock of Mediterra- 

 nean and American sponges, and presented several valuable specimens to the Museum of 

 the Society. Messrs. Weeks and Potter of Boston, have also been very kind in the same 

 way, and have presented to the Society's Collection, among others, the handsome specimen 

 figured on PL 16, fig. 21. 



' Considerable additions have been made to this paper since it was read. 



MEMOIRS BOST. SOC. NAT. niST. VOL. n. 121 (481) 



