PTYCHODERA FLAVA. 727 



island of Kwato opposite to Kogeia, within easy distance of Samarai, and left on board 

 the S.S. Titus on March 28th, bound for Sydney by way of Sudest and the Solomon 

 Islands, the full enjoyment of this interesting voyage being marred by intermittent 

 attacks of fever. 



We passed Sydney Heads and entered Port Jackson on April 20, 1896. I spent 

 upwards of two months at Sydney, where I was accorded working space in the Biological 

 Laboratory of the University by Professor W. A. Haswell, F.R.S., and was thus able to 

 examine some of the material which I had collected, every facility and kindness being 

 showered upon me by Professor Haswell and by my friend Dr J. P. Hill. I was also 

 made free of the excellent library of the Linnaean Society of New South Wales, by 

 the courtesy of Mr J. J. Fletcher, M.A., and received valuable information from the 

 Director of the Australian Museum, Mr R. Etheridge Jr. and from Mr Charles Hedley 

 and Mr Thomas Whitelegge. I learnt from Mr Hedley that Nautilus macrom'phalus was 

 definitely known as the " Isle of Pines Nautilus " and this practically decided me to 

 wend my way to New Caledonia. I therefore left Sydney on July 2, on board the 

 Messageries Maritimes S.S. Tanais bound for Noumea, making the passage through the 

 marvellous barrier reef of New Caledonia on the fourth day out from Sydney. As some 

 days must elapse before I could secure a passage to the Isle of Pines I made arrange- 

 ments through the instrumentality of gentlemen to whom I had brought introductions 

 from Sydney to accompany the Breton pilot, M. Le Ravallec, in the pilot-cutter to the 

 lighthouse on the He Ame"dee, about twelve miles out from Noumea, where the pilots 

 await the arrival of steamers. 



On the shore of Ame"dee I obtained my first specimens of a remarkable species of 

 Enteropneusta, Ptychodera flava, which I afterwards found more plentifully at the Isle 

 of Pines and also on the weatherside of Lifu, that is, on the side opposite to that on 

 which Sandal Bay is situated. From the point of view of my own experience the 

 observation of this species in the living condition, subsequently enhanced by the study 

 of its organisation, threw a flood of light upon the structure of this group of burrowing 

 " worms," which respire by means of gill-clefts, and it seemed to me that Pt. flava 

 should be regarded as the type of the Enteropneusta from a morphological standpoint 

 as it actually is upon chronological grounds, an opinion to which subsequent examination 

 lent additional support. 



It is a remarkable feature of morphological inquiry that one worker should find so 

 many points of comparison between distantly related groups where another, often a very 

 eminent authority, sees nothing of the kind; others again engaged upon similar in- 

 vestigations but starting with different premises ignore utterly the existence of groups 

 of animals which seem to bear upon the matter. For example, I am ready to affirm 

 with considerable confidence that the unpaired hollowed "roots" which pass between the 

 medullary canal of the collar region and the epidermis, where they join the intra- 

 epidermal fibrillar plexus in Ptychodera flava and in allied species, belong to the same 

 category, in other words, are homologous with the pineal outgrowths of the primary fore- 

 brain of Vertebrata. This is a conclusion which may possibly be supported by further 

 observations, but can hardly be submitted to the test of experiment, and must therefore 

 ever fail to convince the rightly sceptical. 



