THE FAMILY OF THE DESMACIDINAE. 157 



That is a total of 162 species. As I have mentioned before, 

 I had not the ivliole literature on the subject at my dis- 

 posal. So this number might be augmented still. But 

 on the other hand we may hope that our knowledge about 

 these species will go on increasing and then, I am sure, 

 many will be shown to be synonyms. 



It is rather a remarkable fact , that the more one stu- 

 dies the systematical arrangement of Sponges, the more one 

 becomes convinced, that many species are identical. The 

 result of my studies on the Desmacidinae has been that 

 plenty of synonyms have been described; when I pre- 

 sumed this to be case , I have united them , but I have 

 never felt the necessity of making two species from one ! 

 Schmidt has shown in what manner Sponges can vary ; 

 F. E. Schulze has given many examples in his splendid 

 studies on Ceraospongiae , especially in his: »Die Familie 

 der Spougidae." Both Schmidt und Schulze have de- 

 monstrated that the word » species" is to be used in a 

 very wide sense. 



Literature. (In alphabetic order). 



In the following list of books used, I have only given 

 the principal titles , not the complete enumeration. I hope to 

 publish soon a complete list of titles of those books and 

 articles in which there has been made mention of Sponges : 

 I refer to that paper. 



H. M. U. DE Blainville, Manuel d'Actinologie. Paris 183'! — 37 [Actinol] 

 J. S. BowERBANK, A Monograph of the British Spongiadae. [M. Br. Sp.] Vol. 



I (1866), Vol. II (1872), Vol. Ill (1874). 

 I) In the several above mentioned numbers of the Proceedings 



of the Zoological Society of Loudon. [Proc. Z. Soc] 



Notes from the Leyden ]VIuseuixi , "Vol. II. 



