96 JOURNAL OF THE 



NOTES ON THE DEVELOPMENT OF SOME 

 SPONGES.* 



BY HENRY V. WILSON. 



The following notes deal with the genmuile develop- 

 ment of Esperella fibrexilis (n. sp.) and Tcdania Briicei 

 (n. sp.), to which are added a few observations on the ^<g% 

 development of Tedanione foctida (n.g.) and Hircinia acuta. 

 Esperella fibrex. is a small silicions sponge abnndant 

 near Wood's Holl, Mass. The others are Bahama forms 

 found at Green Turtle Cay, the two silicions sponges, 

 Tedania and Tedanione, being closely related. 



During the summer, Esperella and Tedania contain great 

 numbers of embryos in all stages of development, and if 

 the sponges are kept in aquaria for a few hours, some 

 of the embryos will pass out through the oscula. The 

 embryos thus set free are solid oval bodies covered with 

 cilia, and are quite like the <t^g larvae of many silicions 

 sponges. They swim about for a day or so and then 

 attach themselves to the wall of the dish, flatten out and 

 undergo a metamorphosis. When the embryos inside 

 the mother are examined, they are found not to be ^'g'g 

 embryos, but true gemmules; /. <?., internal buds. 



I will first describe the development of Esperella. The 

 mesoderm of Esperella contains cells, which differ greatly 

 in size and general appearance, though they shade one 

 into the other. Some of the cells are much larger than 

 the rest and have plump bodies, which stain well. Such 

 cells congregate together and form irregular groups, in 

 which the cells are rather closely packed. The group of 

 cells rounds itself off, the outer cells becoming flattened 



'-■Published by permission of Hon. Marshall McDonald, U. S. Commissioner of Fish 

 and Fisheries, in the Journal of Morphology, Volume V, No. 3. 



