BY WILLIAM A. UASWELL, M.A., B.Sc. 607 



the otlier render it one of tlie most interesting of the ' Vermes,' 

 hfis hitherto only been observed in European seas. The present 

 species, which I propose to name P. australis, was obtained on 

 two occasions during the dredging work carried on under the 

 auspices of the Trustees of the Australian Museum, at a depth 

 of fifteen fathoms off Ball's Head, in Port Jackson. It differs 

 very widely from its European congener in the nature of its 

 shelter. A number of individuals inhabit a large irregular 

 £;emi-gelatinous sac, about six inches long and three or four wide, 

 and open at both ends. The walls of the sac, which are about i 

 to ^2 an inch in thickness, and are tolerably tough, are composed 

 of numerous fine threads closely felted together, and in these 

 walls, in wideish irregular spaces among the felted threads, lie 

 the worms, the head projecting externally ; the inner surface of 

 the sac is lined by a dense glistening layer of the same material as 

 the rest. The whole substance of the sac is of a purple colour. 



The worm presents a cylindrical body, sometimes as much as 

 two and a half inches in length and an eighth of an inch in 

 thickness, and slightly dilated at the hinder end. The head 

 bears a crown of slender filiform ciliated tentacles two-thirds of 

 an inch in length and some hundreds in number, borne on a 

 lophophore, which is continuous behind, but divided in fronts 

 the two limbs each becoming rolled on itself in a series of three 

 and a half spiral turns. The lophophore is vertically ribbed, 

 the ribs being continuous with the tentacles, into which the 

 lophophore is, as it were, frayed out. The front portion of the 

 body, together with the tentacles, is of a dark purple ; the hinder 

 portion is reddish, owing to the blood-vessels shining through. 

 JN'umerous embryos were found enclosed in the spiral of each 

 half of the lophophore. The stages observed do not materially 

 differ from those of the European species, but I have not yet 

 succeeded in finding fully-formed Act Inotro dice. 



The movements of the animals were exceedingly sluggish, a 

 peculiarity wherein it differs very markedly from the European 



