NOTES ON 



SOME JELLY-FISHES FEOM 

 OKHAMANDAL IN KATTIAAVAR 



COLLECTED BY 



MR. JAMES HORNELL IN 1904-5, 



BY 



EDWARD T. BROWNE, M.A., F.L.S. 



SOME years ago Mr. James Hornell very kindly sent to me four jars of unsorted 

 plankton and a jar containing specimens of Cassiopea. The plankton was. collected 

 off the coast of Okhamandal, at the entrance to the Gulf of Kutch, on the north-west 

 coast of India, during December, 1905, and January, 1906. 



The plankton was thoroughly searched for jelly-fishes, and as there were no records 

 of their occurrence along that part of the Indian coast for several hundred mites any 

 results would be of interest on the geographical distribution of species. 



It soon became evident that the collection was more or less a failure ; at least, from 

 my point of view. There was a decided scarcity of jelly-fishes, and an unreasonable 

 amount of very fine mud in the jars, so fine that it took a whole day to settle. The 

 mud not only clung tight to, but clogged up and spoilt everything in the plankton. 

 The scarcity of jelly-fishes may be due to the collecting having been done at the wrong 

 season of the year, or at stations too close inshore. 1 



1 Possibly this paucity was due to the fact that the time of collection was coincident with 

 the period when the temperature of the surface water off the Kattiawar coast is at its lowest, 

 as this factor would be likely to influence reproduction adversely, especially in the case of the 

 Ilydromedusse. In the tropics I have found that numerous groups of animals have two well- 

 marked reproductive maxima in the year, and in the majority of cases these are roughly coincident 

 with the equinoxes. Such seasonal periodicity is the most probable reason for the scarcity of 

 Hydromedusse at the time I visited Kattiawar. In contrast with this, the abundance of the 

 Hydroid fauna characteristic of the littoral waters is notable. Judging from my experience 

 elsewhere in India, I am inclined to think that March and April together with September and 

 October are the months when plankton is most likely to be specially abundant both in species 

 and in bulk in the Gulf of Kutch. Faunistic investigations should give the richest results at 

 these seasons. J. H. 



151 



