72 Memoirs of the Indian Museum. [Voi,. V, 



In this brief description I have not attempted more than to give a concise state- 

 ment of the characters that seem to be of specific importance. Only five adult 

 specimens are available for examination and, so far as I can judge from the species 

 of other families that I have examined in much larger numbers, the so-called anato- 

 mical characters of the Actiniaria are liable not only to great individual variation 

 but also to much momentary change in correlation with expansion and contraction 

 of the muscles and mesogloea, apart altogether from the fact that distortion is almost 

 inevitably produced in the course of preservation. 



In external appearance Gyrostoma glaucum bears some resemblance to von 

 Ehrenberg' s figure of Entacmaea olivacea [ ( = Paradis olivacea, Klunzinger), but 

 differs therefrom in the greater relative length of its outer tentacles. 



G. glaucum has been taken as yet only in the Chilka Lake, in which it appears to 

 be very scarce. It occurs both in the main area and in the outer channel. A single 

 specimen was taken near the mouth of Rambha Bay in February, at a depth of 

 between 5 and 7 feet and in water of a sp. gr. of roo75, while four others of much 

 smaller size were obtained in the channel between Satpara and Mahosa in March, 

 from about the same depth and in water of sp. gr. 1-02575. Three others 2 of still 

 smaller size and evidently immature were found in the oyster-beds at Manikpatna 

 in the same month. 



Family SAGARTIIDAE. 

 Subfamily METRIDIINAE. 



In discussing the species of this subfamily found in the Gangetic delta inex- 

 perience led me in 1907 into a taxonomic error, but this error, having some biological 

 justification, has proved not unprofitable in considering the actinians of the Chilka 

 Lake. In 1907 3 I ascribed three forms from Port Canning to the genus Metridium 

 and to the species described by Stoliczka* in 1868 and 1869 as Sagartia schilleriana. 

 One of these, there is no doubt, was identical with that species, of which my speci- 

 mens were topotypes in the strictest sense of the term and of which the actual types 

 are still available for comparison in Calcutta ; another I described as a variety (exul) , 

 while the third I regarded as the young of the second. These three forms are here 

 placed in three distinct genera, of which two are described as new, while Stoliczka' s 

 species is left in Metridium. 



As the two new genera are both represented in the Chilka Lake, it will be 

 convenient to discuss here the relationships of one to the other and of both to Metri- 

 dium. Differences may first be noted. The species of Metridium are all anemones 

 with a well-developed basal disk by means of which they cling firmly to solid objects. 



1 See Zoologica it, Phytozoa, pi. viii. fig. vi, in Symbolicae Physicae, edited by O. Carlgren (1899) 

 and Klunzinger's Korallthiere des Rothen Meeres 1, p. 70, pi. v, fig. 7, pi. viii, fig. 8 (1877). 



% These had only 24 tentacles arranged in two circles, an outer circle of 8 and an inner one of 16; 

 the latter was, however, incompletely differentiated into two subsidiary circles. 



3 Rec. Ind. Mus. I, p. 35. 



* Proc. Asiat. Soc. Bengal, 1868, pp. 174, 263, and Journ. Asiat. Soc. Bengal, XXXVIII (2), p. 31 (1869). 



