PROCEEDINGS OF THE SOCIETY. 269 



by this gentleman, I obtained it once more at the same spot, after an 

 interval of 21 years. Lastly, I found it in the Surrey Commercial Docks, 

 at a Quekett Club excursion on October 5 of last year. 



This species is also known from Germany. It is always found 

 attached to the stems of the hydroid Gordylopliora lacustris, with which 

 it seems to have entered into a symbiotic arrangement for mutual support 

 and food supply. 



I cannot enter into any description, beyond saying that it is a 

 very small species of a marine type, with a circular lophophore of only 

 eight tentacles. The specimen under the Microscope is the first ever 

 prepared with tentacles fully extended. 



2. Victorella symbiotica. Last year* I described a second species of 

 this genus, which was brought by 'Dr. Cunnington from Lake Tan- 

 ganyika. It was found completely imbedded in a sponge, the long 

 narrow tubes penetrating through its substance, to enable the creature to 

 expand its tentacles above the surface of the sponge. 



This species also seems to possess sufficient intelligence to see the 

 advantage of entering into a similar symbiotic arrangement with a sponge 

 for protection and food supply. 



3. Pott siella erecta. — In 1884 Mr. Edw. Potts, of America, published 

 a very short account, without figure, of a new Polyzoan under the name 

 of Paludicella erecta, which he had found attached to submerged stones 

 in the Pennsylvania Canal in his neighbourhood. In 1887 Professor 

 Kraepelin, of Hamburg, having obtained some specimens from Mr. Potts, 

 changed the generic name into Pottsiella in his monograph of the 

 German Fresh-water Bryozoa, having recognised that its affinities are 

 quite different from those of Paludicella. 



Last August, at my request, Mr. Potts was good enough to send me 

 some living specimens to Boston, where I was able to prepare a few 

 fully expanded, and the specimen under the Microscope is the first one 

 so obtained. Later in the year, after the cold weather had set in, Mr. 

 Potts sent me some stones with the died-down tubes of this species, and 

 from the creeping stolons of some of these, new tubes have been formed 

 in my aquarium, and for the first time in England I have seen the 

 living Pottsiella expand its circular lophophore of about twenty-two 

 tentacles. 



4. Urnatella gracilis is another rare American species which was 

 discovered and described by Leidy in 1851, in the Schuylkill River. 



The same stones lately received from America to which Pottsiella is 

 attached, have also a number of Urnatella, and here again I revived in 

 my aquarium the first living specimens ever seen in this country. 



Urnatella is a fresh-water representative of another marine type — 

 Pedicellina. 



5. Arachnoidia Ray-Lankesteri. — In 1903 Mr. Moore brought this 

 remarkable Polyzoan from Lake Tanganyika, where it was subsequently 

 found again by Dr. Cunnington, and the slide exhibited here is from 

 this expedition of 1905. It is also of a marine type with rounded flat 

 cells, closely adhering to shells and stones, with a tall erect tube at one 

 end, from which the animal protrudes its circular lophophore of sixteen 

 tentacles. 



* Proc. Zool. Soc. London (1907) pp. 250-257 (2 pis.). 



