356 L. MURBACH. 



found higher up on the polyp. The largest, and therefore the 

 oldest buds are borne below the middle of the length of the 

 body on single short stalks. From one to ten buds may be 

 found on one polyp. 



Scattered everywhere among the polyps bearing medusa 

 buds are others that appear to be sterile individuals. When 

 there are only a few of them they are not conspicuous, and at 

 a time when none of the polyps of a group had any medusa 

 buds they might not at all be noticed. They resemble the 

 others in all respects except that they are more slender and 

 taller, being often 2 to 3 mm. in height, and that they lack 

 any traces of medusa buds, while those around them are very 

 prolific. I cannot understand this sterility of individuals so 

 nearly like the reproductive ones, unless it be a functional one, 

 and is to be interpreted as the beginning of a division of labour 

 in these simple polyps, which in time will lead to a more 

 striking polymorphism. Allman^ in his Gemmaria im- 

 plexa has observed a similar difference, of which he says, 

 " In no case can it be regarded as reducing the hydranth to the 

 condition of a blastostyle.'^ 



Shortly before the Corynitis polyps were found here I had 

 been taking in the tow a small medusa bearing on its two 

 tentacles some peculiar stalked organs, not unlike stalked 

 Protozoa. When I found them to be an integral part of the 

 tentacles it became evident that the medusa before me was 

 Gemmaria, especially since other characters agreed. The ex- 

 planation of the presence of this form in our harbour was 

 soon apparent when the medusse, freed from the Corynitis 

 polyps, were found to have exactly the same characters, and so 

 proved to be Gemmaria. To leave no doubt whatever, one 

 medusa was observed continuously while freeing itself from its 

 polyp nurse by repeated contractions, and until it had suffi- 

 ciently expanded to recognise its distinctive characteristics. Its 

 umbrella was more spherical, and its tentacles more contracted 

 one shorter than the other, — as were also its stalked organs 



1 'A Monograph of Gymaoblastic or Tubularian Hydroids/ 1871-2. 



