Being Transactions of the S. Afr. Phil. Society. Vol. XVII. 161 



(c) Eggs, larvae, oviposition, breeding season. 



(d) Lophophoral organ, lophophoral gap, epistome. 



(e) Sensox'y organs. 

 (/') Circulation. 



(a) Mode of Occurrence, Formation of Tube, dx. — Most of the 

 animals examined were found in a limestone of recent origin which 

 occurs on the shore and on the sea- bottom in False Bay. It con- 

 tains a large quantity of rounded sand-grains embedded in a 

 calcareous matrix, which is made up of recent shells. It is bored 

 through by worms, lamellibranchs, and sponges. It seemed at 

 first pretty conclusive that the Phoronis had bored into this lime- 

 stone, as, in most of the cases, where they were chiselled out or 

 the limestone broken, they were found to tit closely the cavities 

 in which they lay, and as the tubes were coated on their out- 

 side with a layer of sand-grains apparently pushed aside when 

 the limestone itself was dissolved. The presence, however, of 

 numerous sponge spicules in this coating of the tube seemed to 

 indicate that the cavity had originally been made by a sponge. 

 Further, the fact that other specimens were found in the interstices 

 of Polyzoa and worm tubes, in one case in the tube of a Serpula 

 which had left or been ejected, and in another case in the loculi of 

 the base of a barnacle shell, is evidence in the same direction. I 

 may add also that no acid reaction was obtained from living 

 specimens. On the whole, the balance of evidence seemed to 

 indicate that this Phoronis is not a limestone-boring animal, and 

 that colony formation, which, however, is not a very characteristic 

 feature of this species, is merely due to local conditions favouring 

 growth at a particular point. 



The part of the tube projecting from the material in which the 

 animal occurred varies much in length, being usually about 4 to 

 6 mm., but sometimes much longer, or entirely absent. This part 

 of the tube was very flexible, and covered with a substance similar 

 to that of its surroundings. The stone was found to be covered with 

 a greyish coating of debris, held together by a sticky substance. On 

 one or two occasions large starfish, which were in the tank, were 

 observed to remain for some time in the stone and clear off this 

 coating without, however, injuring the Phoronis. It would appear 

 that this coating may be produced by the action of the Phoronis 

 themselves. Sections of the projecting part of the tube showed that 

 the debris was not only adherent to the outside of the tube, but was 

 included in the substance of the tube itself. For the proba!)le origin 

 of this mucous substance and particles, see below. In some species 

 the foreign substance adhering to the tube has been described as the 



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