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On Spongilla fragilis found in the Thames. 

 By B. W. Priest. 



(Bead January 22nd, 1886.) 

 Plate XV. 



In November, 1882, I had the honour of reading a paper to 

 yon on the Statoblasts of the Fresh-water Sponges, at the same 

 time, as you will recollect, enumerating the different species 

 then known, but I was not aware of the numerous Fresh-water 

 Sponges which were being found and classified, in the United 

 States, by Messrs. Potts, Mills, and Thomas. Through the kind- 

 ness of Mr. Crisp, I was brought into communication with Mr. 

 Thomas, of Chicago, who was most generous in supplying me 

 with several of the species met with in America. 



Among those sent was one which forms the subject of the 

 present communication, viz., Spongilla fragilis, so named by 

 Professor Leidy, but previously and first made known by Mr. J. 

 K. Lord, who found it in Lake Osogoos, and other lakes and 

 rivers, tributaries to the Columbia River, on the Eastern slopes 

 of the Cascade Mountains, about 6,000 feet above the level of 

 the sea. Out of compliment to the discoverer, the late Dr. 

 Bowerbank named it Spongilla Lordii, the type specimen of 

 which is, I believe, in the Natural History Museum, South 

 Kensington. I can find no record of its being found again 

 until Professor Leidy met with it. Dr. Bowerbank had pre- 

 dicted that it might be found one day in the United States, as 

 he had observed fragments of similar spicules in the infusorial 

 earth collected and sent to him from that quarter. 



The Sponge itself is sessile, coating and encrusting stones 

 and pieces of wood and weeds ; structure fragile — hence the 

 name given by Professor Leidy — crumbling so much that where 

 there is a dashing of water, as on the banks of the river, most 

 of the skeleton, according to Mr. Mills, of Buffalo, is washed 

 away, leaving in many cases the statoblasts in a bare continu- 



