I 26 Proceedings of the Royal Physical Society. 



the material which forms the basis of this paper was collected. By 

 that date, unfortunately, Anrelia aurita had just passed through the 

 ephyra stage, and though there were a few larval forms in the collection, 

 these were so few that they were disregarded. The material in the hauls 

 consisted almost entirely of very small, immature adults, whose diameter 

 varied from 7 to 27 mm. The hauls were taken in Loch Ridden, near 

 Ormidale Pier, at a depth of from 3 to 5 fathoms, and I am greatly indebted 

 to Mr Gray, who was then Curator of the Marine Station, for help readily 

 given. We were fortunate in getting all we required in two successive 

 trials, though at the time the sea was extremely rough in this usually 

 quiet loch. A cheese-cloth net, worked from the S.Y. " Mermaid," was 

 the collecting instrument employed. Except for a few sagittae, the contents 

 of the net were almost entirely of one species of immature jelly-fish. As has 

 been said, the intention was to return to the same area about July and 

 to collect adults. But so few jelly-fish were seen in the Clyde during 

 the summer and autumn of that year, 1903, that it was absolutely impossible 

 to gather anything like the necessary number. Thus it came about that 

 as the ephyrse had not been found, and as the adults could not be 

 found, the examination of the immature adults was delayed. The material 

 collected was, however, carefully preserved, according to the directions 

 given by Browne, 1 and so successful has this preservation been that the 

 specimens are still in wonderfully good condition. The somewhat laborious 

 work of examination of these tiny organisms takes considerable time, and 

 as it has been done at odd moments, often separated by prolonged intervals, 

 the observations have only now for the first time been tabulated. 



I have to thank Mr James Ritchie of the Royal Scottish Museum for 

 his kindness in making for me the sketches which illustrate this paper. My 

 thanks are also due to Professor J. Cossar Ewart and to Dr Ash worth, who 

 kindly let me have the use of the Edinburgh University Zoological Laboratory, 

 as well as to Professor J. Arthur Thomson for permission to work at the 

 Aberdeen University Table at Millport Biological Station. Part of the 

 expenses incurred in connection with this research has been met by a grant 

 kindly given me by the Carnegie Trustees. 



0-kigina.l Research. 



The number of the principal organs in Aurelia seems to be definitely 

 fixed not later than during the ephyra stage, and a typical ephyra, of 



1 Browne, E. T., I.e., p. 108. 



