69 



leaf. In some case the ground-colour of this species is white, 

 or nearly so, harmonizing well with the lower parts of the 

 leaves. S. cymodocealis, while often in colour and markings 

 resembling the darker-green form of the former species, is 

 usually variegated by darker markings, and the dorsal area 

 often shows pinkish shades, thus harmonizing to a striking 

 degree with the various growths that so often encrust the stems 

 of Cymodocea. Of the plant which is the host of Stenochiton 

 pallens we have, as before stated, no actual knowledge, but 

 we are surely justified in deducing from the habits of its 

 congeners that it lives on a plant probably belonging to the 

 same order Fluviales, that the portions of the plant it affects 

 are probably pale brown, buff, or cream in colour, and also 

 that" as only dredged specimens have been found, the plant is 

 either a deep-water species or a pale and colourless variety 

 growing in deeper waters ; or perhaps it lives upon the dying 

 or dead leaves, with which undoubtedly ite colour would well 

 harmonize. 



Food. — I have attempted to keep the three first-named 

 species in an aquarium, supplied with their respective host 

 plants, but although care was taken to keep the temperature 

 cool, they all died, and no results were obtained. Possibly 

 these plants do not throw off sufficient oxygen. I think there 

 is little doubt that Stenochitons live on the plants of the order 

 Fluviales, are nocturnal, in common with most of the Poly- 

 plaeophora. I have seen portions of the stems of C i/modocea 

 eaten in a way that would suggest that it had been done by 

 the Stenochiton. Further, the Posidonia which is frequented 

 by two of the genus is almost invariably clean, no small 

 encrusting growths being present, and therefore it is doubtful 

 whether they would find any other food than the leaves of 

 Posidonia. I am indebted to Mr. J. M. Black for the indentifi- 

 cation of the two marine plants referred to. There is a close 

 outward resemblance between Posidonia australis and Zostera, 

 tasmanica, and therefore, owing to> my inability to find speci- 

 mens of the u sea grass" I have referred to> as Posidonia 

 australis in flower or fruit, it is possible that Mr. J. M. Black, 

 who has been good enough to examine and identify for me the 

 specimens I sent him, may not have had sufficient data for 

 accurate determination. He says, "Judging only by the 

 breadth of the leaves and the nervation, the specimen sent is 

 Posidonia australis, and not a Zostera." I think it not unlikely 

 that the two species of Stenochiton I have referred to as living 

 on Posidonia may live on Zostera tasmanica just as freely. 



Classification. — The partial elucidation of the life history 

 of members of the genus Stenochiton recorded in the fore- 

 going, which supplies strong circumstantial evidence that not 



