I9 T 5-] Fauna of the Chilka Lake : Coelenterates. 103 



with its hydroid generation. All the orders of the group except the Trachomedusae 

 and the Hydrocorallinae are represented, but the Narcomedusae and the Siphono- 

 phora each include only one casual visitor. The true hydroids are better repre- 

 sented; among the Calyptoblastic families, the Campanulinidae have a single 

 medusa (a casual visitor), and the Campanulariidae two hydroids, each belonging 

 to a separate genus, as well as a medusa that may very well be co -specific with one 

 of the hydroids. One Calyptoblastic hydroid is a casual visitor, while another 

 establishes itself in the outer channel, in which a medusa belonging to the same 

 group was also found as a casual visitor, in the salt-water season. The Gymnoblastea 

 are represented by three hydroids, two of which are permanent inhabitants of the 

 main area of the lake, while the third was found only in the outer channel and 

 in the salt-water season. 



Most of the casual visitors and periodic immigrants are marine species of wide 

 distribution. Of the four free-swimming forms included in these categories one is 

 cosmopolitan and one Indo-Pacific, one is widely distributed in the Bay of Bengal 

 and the neighbouring seas, while the fourth, though only known as a medusa from 

 the outer channel of the lake, is perhaps the other generation of an Indo-Pacific 

 hydroid found with it. Of the three fixed forms that are not permanent residents 

 two are Indo-Pacific while one was described from Ceylon. 



The two permanent residents, on the other hand, are both species that were 

 originally described from the Gangetic delta and are as yet known only as inhabi- 

 tants of brackish water on the east coast of India. 



Order NARCOMEDUSAE. 



Family AEGINIDAE. 

 Genus Solmundella Haeckel. 

 Solmundella bitentaculata (Quoy and Gaimard). 



1904. Solmundella bitentaculata, Browne, Faun. Geogr. Maldives and Laccadives 



H, p. 741.pl. lvi, fig. 3. 



1905. Solmundella bitentaculata, id., Rep. Ceylon Pearl Fish. IV, p. 153, pi. iv, 



figs. 1-6. 

 1910. Solmundella bitentaculata, Mayer, Medusae of the World II, p. 455, fig. 

 301 (p. 457). 



An excellent figure of this peculiar little medusa as it appears when contracted 

 is given by Browne (1904). In his paper of 1905 he gives further particulars. 

 Mayer regards the Aeginopsis mediterranea of Müller as no more than a variety. If 

 this is so, the species occurs in all seas but has become sufficiently differentiated in 

 the Mediterranean to be distinguished there as an endemic race. As Mayer points 

 out, referring to Vanhoffen's report on the Narcomedusae of the ' Valdivia ' (Nar- 

 comedusen der ' Valdivia ' Exp., p. 45), "Solmundella is the most widely distributed 

 Narcomedusa known, ranging from the North Atlantic, through the tropical Pacific 



