NOTE ON THE METAMORPHOSI8 OP THE 

 SPONGE-LARVA. 



BY 



G. C. J. VOSMAER. 



With Plate XIV. 



Dr. O. Maas published in the Zool. Anzeiger (n° 316, 1889) 

 a short note on the 'ectoderru' of Spongilla, in order to prove 

 that Goette was wrong in suggesting that the larval 'ectoderm' 

 disappeared and that the whole sponge originated from 'entoderm'. 

 Dr. Maas' result is : — 'Das Ectoderm der Spongilla-Larre geht 

 nach eingreifenden Veranderungen wahrend der Metamorphose 

 vollstandig in das Epithel des jungen Schwammes über'. 



I am bound to say that I never believed in Goette 's rather 

 extraordinary statement. However, as I had no opportunity to 

 study the same genus, but only.related Cornacuspongiae, I could 

 hardly attack Goette. I am therefore much interested in Dr. 

 Maas' paper and intend to give a few statements of what I found 

 in a sponge which probably belongs to the genus Myxilla. 



The adult sponge ressembles very much M. rosacea o. s., 

 but it does not possess so many kinds of spicules. I cannot en- 

 ter into details about the systematic position of this sponge. This 

 will be done in my Monograph, to be published in the 'Fauna 

 and Flora of the Bay of Naples. 



The free larva consists of an inner mass of various cells, the 

 coenoblastem of Marshall, which is covered all over by cylin- 

 dric epithelium. This epithelium soon exhibits two very distinct 

 portions. By far thé greater part bears ciliae; */, — '/ 8 of the cir- 

 cumference however is absolutely destitute of them. The flagella- 

 ted cells are very slender ; the others are moi'e or less cubic. I will 



