PORIFEEA 



17 



which lead a roving life for a brief period, and then settle 

 down, and proceed to extend as above said. 



I have observed in one species at least (it occurs in several 

 others) another method of propagation. In Tefhya lyn- 

 curium, at the end of summer, the surface becomes 

 covered with little protuberances, which at length become 



Fig. 4:.Tethya lyncurium budding, natural size. Inset, a freed 

 bud enlarged about 6 times 



stalked and furnished with a radiating arrangement of 

 spicules ; then these break away, and are carried by currents 

 to other localities, where they affix and grow to the form 

 of the parent. 



A photograph of one of these sponges, showing this mode 

 of reproduction, is shown in Fig. 4. It is from a living speci- 

 men before me as I write. 



The sponges are divided into four families as follows : 

 Myxospongia. Those in which little or no skeletal 



