TUBE OF PANTHALIS. 345 



venience, referred to the threads secreted by Panthalis as 

 " mucns-like " but I don't intend thereby to express an 

 opinion as to the nature of the material of which they are 

 composed. They are secreted by Eisig's spinning glands 

 and appear to be very similar to those formed by Polyodontes 

 maxillosus, which Eisig describes as "chitinous." They 

 are very slightly, if at all, soluble in boiling caustic potash. 



As explained at the outset, my chief object in these 

 observations was to ascertain whether Panthalis made 

 the tube which it inhabits and if so how ? and I think I 

 have satisfactorily answered both questions. 



The tubes of the Acoetidse, from the absence of any 

 membranous lining, and their general construction, would 

 appear to be unique amongst annelids. In this connexion 

 see Quatrefages' reference to Acoetes pleei, (Histoire 

 Naturelle des Amieles, I, p. 216), Eisig's account of Polyo- 

 dontes maxillosus, and Ehler's description of EicarcJie 

 tuhifex (Florida Anneliden, pp. 54-6). No minute 

 description has previously been given, but from the 

 similarity of their organs, it seems probable that the tubes 

 of all these worms will more or less closely resemble 

 each other. 



In closing this paper I would take the opportunity of 

 expressing my great appreciation of, and gratitude for the 

 advantages afforded me at the Port Erin Biological Station, 

 to which the success of my experiments has been largely 

 due. Absolute stillness was a most important factor, and 

 I am greatly indebted to Prof. Her dm an, both for the steps 

 which he took to ensure this, and also for very much 

 valuable advice and assistance. To him this paper is 

 really due, as excepting for his kindness in making special 

 journeys with me on August 25th, and September 30th, 

 1894, to the ground where Panthalis is to be found, these 

 observations would have been impossible. 



