722 Proceedings of the Royal Irish Academy. 



30tli, cluriiig October, and until ]\'oveinber 13th; only a few 

 specimens in eacli tow-netting. 



In 1897, the ^Misses Delap record the species in their notes 

 from February to Xovember. It was very abundant in July 

 and September. 



In 1898, it appeared in ]March and disappeared in iSTorember ; 

 very abundant in July and August. 



A variation in the number of radial canals occurred in 

 only seven of the 450 specimens (taken on August 28th, 

 1898) :— 



One specimen with one canal and one radial gonad upon it. 



Five specimens with three canals and three gonads. 



One specimen with five canals and five gonads. 



Other species of Olelia were taken; but as the specimens 

 were in formalin they were not identified. 



OctorcMs gegenbauri, Haeckel. 



OctorcMs gegeniauri, Haeckel, 1879, p. 171, Taf. xiii. ; Browne, 

 1896, P. Z. S., p. 494. 



This Medusa has only been recently added to the British 

 Fauna. A solitary specimen was taken at Plymouth in 1895, 

 and previous to that date it was only known in the ]!Iedi- 

 terranean. 



In September, 1896, I took a young stage in Valencia 

 Harbour, and the Misses Delap fortunately captured two fine 

 specimens in 1897, and sent them to me, along with good 

 sketches fi'om life for identification. As very little is known 

 about this species, a description of the Valencia specimens may 

 be of use. 



September 21st, 1896. This specimen was not in good con- 

 dition when captured, so that full details cannot be given. 

 Umbrella about 6 mm. in diameter ; manubrium about 6 mm. in 

 length. Four perradial tentacles and four interradial bulbs, 

 from which tentacles probably develop later on. Many tubercles 

 on the margin of the umbrella, and probably each one with a 

 lateral ciiTUs. Eight marginal sense-organs, each with about 

 10-12 otoliths, arranged in a semicircle. Gonads present along 

 the outer third of the radial canals on the sub-umbrella, and 

 also on the radial canals along the peduncle of the stomach, 

 but quite immature. The Medusa was perfectly colouiless, 

 just like clear glass in water. 



