Mr. C. Collingwood on Oceanic Forms o/Hydrozoa. 311 



the deck, ran about like a frantic oianiac, so that it took several 

 men to catch him, and, when secured and the proper remedies 

 applied, he rolled about for a considerable time, groaning with 

 pain. His arm was i*ed, inflamed, and swollen, and remained so 

 for some hours after the occurrence. 



One circumstance in relation to these large PhysaliiE struck 

 me as being very remarkable. Each one as it floated by had 

 beneath it what at first I took to be its mass of tentacles and 

 polypites; but on more close observation I found that the 

 appearance was due to a shoal of small fishes accompanying the 

 hydrozoon under protection of its appendages. The fishes were 

 of various sizes, from 2 to 6 inches long, transversely banded, 

 and looking in the water precisely like the pilot-fish {Naucrates 

 ductor) . There were perhaps a dozen of these accompanying 

 fish clustered together beneath the bladder of each Physalia. 

 Every Physalia had its cluster; but this peculiarity was ob- 

 servable — viz. that under small Physalia the fishes were small, 

 while under large specimens they were correspondingly large, 

 being, in fact, always yjroportioned to the size of the man-of-war 

 which they accompanied. Unfortunately I did not discover this 

 curious fact till late in the day ; and when the boat was down 

 in the morning I was unaware of it, or I should have made a 

 point of attempting to secure a specimen of so interesting a 

 fish. 



What the relation is which exists between the fish and the 

 Hydrozoon I cannot say ; but this correspondence between the 

 sizes of the two animals seems to indicate that the fishes do not 

 capriciously select their protecting Hydrozoon. It is known 

 that certain fishes harbour in the threads of some of the large 

 Lucernaridse ; but I believe they have not before been noticed 

 accompanying Physalice. 



The presence of these fishes also accounted for a remarkable 

 thing I had observed earlier in the day. One of the large 

 albicores made a sudden dash at a Physalia (apparently), but did 

 not take it; returning, however, presently to the charge, he 

 made a clean sweep, no trace of the Physalia being left. Doubt- 

 less it was the small fishes which accompanied it, rather than 

 the Physalia itself, which stimulated the albicore's attack. 



Before I quit the subject of the Physophoridse, I must not 

 omit to mention a circumstance which occurred only once 

 during the whole time I was at sea — viz. the remarkable influx 

 of Stephanomiadse, accompanied by other kinds of animals, into 

 Kelung Harbour, Formosa, on the 18th of June. The beautiful 

 organisms I there observed were of the genus Stephauomia, and 

 closely resembled the S. triangularis of Quoy and Gaunard. They 

 were wonderfully sculptured and carved masses of solid jelly, 



