12. Notes 



No 



Preliminary Note on the Occurrence of a Medusa 



(Irene ceylonensis, Browne) ia a. Brackish Pool in 



the Ganges Delta and oa. the Hydroid Stage of the 



Species. (Plate II.fflg,5.) 



By N. Annandale, D,Sc. 



Among other interesting specimens collected last month 

 (Novemher) in brackish pools at Port Canning, Lower Bengal, 

 by Mr. C. A. Paiva, Entomological Assistant in the Indian 

 Museum, are three examples of a Medusa belor ^ 

 LeptomedusEe. The pool in which they were taken belongs to the 

 group in which Stoliczka^ discovered the Polyzoon Membrampora 

 henyalensis and the Actinian Sagartia 5c^i7Zmana thirty-eight years 

 ago. In Stoliczka's time the water of these pools was found by ana- 

 lysis to contain a proportion of about one-third of the amount of the 

 salts ordinarily present in sea water. There is no reason to believe 

 that any permament change in this respect has taken place since 



seasons. 



y great, 

 mixture 



and freshwater characters, with which I hope to deal more fully 

 on another occasion. 



As regards the identity of the Medusa, I have no hesitation in 

 assigning it to Mr. E. T. Browne's * recently described species, 

 Irene ceylonensis^ which was taken by Prof- Herdman^ off^ the 

 coast of Ceylon. The original diagnosis of this species is as 

 follows : — " Umbrella probably watchglass-shaped, much broader 

 than high, with thin walls. Velum narrow. Stomach short, 

 situated upon a long cylindrical peduncle. Mouth with four^ lips, 

 which have a folded margin. Fonr radial canals. Gonads linear, 

 extending from the base of the peduncle to near the margin 

 of the umbrella. Tentacles about 100. Cirri absent.^ Sensory 

 vesicles, one between every two tentacles, each vesicle with a 



single otolith/' 



In one respect the Port Canning specimens differed from this 

 description very noticeably, or rather appeared to do so, mz.^ in 

 the proportions of the umbrella. When I first examined them, they 

 had been in 5 per cent, formol for about twenty-four hours and were 

 in a very perfect state of preservation. In this condition the walla 



its height. 



fro 



greater th 



ever soon began to show changes in these respects, and came 



1 Journ, Asiat. 8oc. Bengal, part n.^ 1869, pp. 53, 61. ^ 



t Tn Herdmau's Ceylon Pearl Fisheries and Marine Biology, iv., I90o^ 



140 



