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XXY. 



ON THE GEODINE GENERA, SYNOPS, VOSM., AND 81DO- 

 NOPS. A CORRECTION. By Professor W. J. SOLLAS, 

 D. So., LL.D. 



[Communicated January 9, 1889.] 



In my Report on the Tetractinellid Sponges of the Challenger 

 Expedition, I have defined the genus, Synops, Vosm., as follows : — 

 " Poriferous and oscular surfaces distinct ; oscules the simple 

 openings of excurrent chones ; pores in sieves overlying incurrent 

 chones." 



My friend Dr. Yosmaer has kindly directed my attention to 

 the last part of this definition, truly remarking that it is at variance 

 with that originally given by him, 1 in which the pores are described 

 as simple, and not sieve-covered openings. At Dr. Vosmaer's 

 request I have re-examined the fine specimen of the type species, 

 Synops pyriformis, Vosm., which I owe to his kindness, and with 

 the result of fully confirming his views. I have, indeed, to confess 

 to an oversight, for there can be no doubt that in Synops, Vosm., 

 the openings of the incurrent, like those of the excurrent chones, 

 are quite simple, and not sieve-covered. 



This character Synops shares with Isops, Soil., and Dr. Vosmaer 

 recognising this, wrote to me some time ago, inquiring whether the 

 two genera should not be merged into one. At that time I was 

 under the influence of the error just corrected, and imagined that 

 in the character of the pores of Synops there existed quite sufficient 

 grounds of distinction. With the disappearance of this imaginary 

 difference, the distinction between the genera to my mind breaks 

 down, and Synops becomes a synonym for Isops. Dr. Vosmaer is 

 now, however, inclined to maintain a distinction, on the ground that 

 the oscules are congregated in Synops in shallow depressions ; this 

 is, however, possibly explicable as a result of growth. Specimens 



1 Vosmaer, Report on Sponges, il Willem Barents," p. 20, 1882. 



