Vol. Ill, jSTo. 2.] Notes on the Freshwater Fauna of India 85 



[N.S.] ^ 



,r 



■HrsLOPiA LACII8TIUS, Carter. 



This is by far fhe most strictly lacustrine of theCteuostome's, 

 being found in perennial pools of fresli water in the centre of 



( 



Memb 



sis; but I have only been able to find it on two occasions, or rather 

 two series of occasions (January and February), and in one pool. 

 Carter's specimens were attached to shells of Paludina; mine were 

 on the leaves of Yalisneria spiralis and were growing in a pool 

 without the slightest shade. Inrnj former note I neglected to say 

 that the tentacles were of uniform length when fully extended. 

 The stolon, which occasionally joins two zooeciaj is quite rudiment- 

 ary and is no more than a narrow^ed posterior portion of the 

 anterior zooecium. It is most apparent at the growing extremities 

 of young colonies, but can occasionally be detected in other in- 

 stances. 



Hislopia is distinguished from Paludicella and Vtctorella 

 by the possession of a well-developed gizzard, as well as by 

 the curious structure of the aperture and the absence of a funiculus. 

 If I am right in regarding Norodonia, JuUien, as synonymous, the 

 genus ranges from Central India to Southern China. I have seen 

 a form^ in the Malay Peninsula which belongs to the Indian 



species. 



PHYLACTOL^MATA 



Plumatella. 



Including Plumatella and Alcyonella according to Allrnan 

 (1878) ; Plumatella and Hyalinella siccovding to JuJlien (1885 j ; and 

 Plumatella according to Kraepelin (1887), 



This genus is probably the most difficult among those repro- 

 sented, in fresh water, because of its great variability both as re- 

 gards individual colonies and as legards races or sub-species and 

 more or less constant varieties. There can be no doubt that the 

 massive agglutinated forms once known as Alcyonella are simply 

 phases, produced by envii*onment, of the same genus, from w^hich 

 they arise and into which they may lapse; but little infoi^mation 

 is available regarding variations produced by external conditions 

 in other respects. The study is further complicated by the fact 

 that although many of the form are probably cosmopolitan, they 



1 By the kindness of Miss L. Thornley, of Liverpool, I have been able to 

 examine specitaens collected by Mr. H. C. Robinson and mf9e]f in auturnn 

 in a small lake near Jalor in the Siamese Malay States. The spirit In wlaoh 

 thev were preserved having dried up, they agree closely with JuUien's de- 

 scription of Narodonia cajnbodiensis, differing from Indian Bpoclmenu found 

 iu January and Febrnary in the ab-*ence of spines at the corn^rn ot the 

 aperture, I cannot regard this as more than a varietal diff*^rence. — N. A., 



12-1^07. 



