234 DISCOVERY REPORTS 



The tubes in which the zooids Hve open at regular intervals on the surface of the 

 colony. In the young branches the substance of the test is transparent enough to show 

 the disposition of these tubes. In the older parts they are reddish brown and can easily 

 be distinguished from the surrounding substance of the test. They run from the axial 

 region of the branch obliquely upwards and are not more than 12 mm. long in the young 

 growing points. They project 3 or 4 mm. from the surface, but as growth proceeds, 

 more and more coenoecial substance is laid down in strata, filling the depressions and 

 increasing the thickness of the test so that the ostia come to lie on the surface of the 

 branch. Any further increase in thickness is accompanied by a corresponding increase 

 in the length of the tubes, so that the ostia always open on the surface and the lips alone 

 project. 



A longitudinal section passing through the axis of an old stem shows the arrangement 

 of the tubes clearly. Their width is almost constant (1-2 to 1-3 mm.) and they are em- 

 bedded in the greyish brown mass of the test, forming the bulk of the colony. Near the 

 ostium the cavity of the tube is wider, and the part remote from the ostium is closed. 

 In the oldest regions, the tubes are 20 to 24 mm. long, but the lower part is closed by 

 a septum so that the zooids occupy only the distal half. 



The lips are triangular projections of the abaxial margin of the peristomial tube, but 

 on some they are shifted slightly to the sides. They are 2 to 2-5 mm. long, and project 

 at right angles to the surface. On older branches they are shorter and thicker. 



Some adjacent branches are attached to each other by the secretion of coenoecial 

 substance. In a few cases the tip of a branch of one colony is attached to the body of a 

 branch of another colony. From this it seems possible to infer that whenever adjacent 

 branches of colonies growing close together touch, they fuse, so that disturbing move- 

 ments in the water may not injure the zooids. 



Each tube is occupied by one zooid and its buds, which in the preserved condition 

 are situated 4 or 5 mm. from the external opening. Owing to their dark colour they are 

 clearly visible through the test. The zooids measure 3-5 to 4-5 mm, from base of body 

 to tip of arms, and are deeply pigmented. The body of a full-grown zooid fits fairly 

 closely in the tube. 



The stolon, which is i to 1-4 mm. long, projects from the basal part of the body and 

 ends in a knob on which the young buds grow. A fully formed zooid bears two to nine 

 buds. The smallest buds are crowded round the tip and in the preserved condition they 

 are very much contracted, with their stalks twisted about one another owing to the effect 

 of the fixative. The buds at the tip of the stolon are the youngest ones. These have a 

 very short body and proboscis. As the stalks lengthen during growth the buds are removed 

 farther away from the parent stolon. When the mother zooid is freed from the tube, 

 one or two buds are seen pressed to the side of the body, a few entangled among the 

 arms, and rarely one or two projecting beyond the tip of the arms. Such a bud is still 

 connected with the parent stolon by its own stalk, which has grown long enough to carry 

 it to its present position. 



The situation of the older buds suggests the possible mode of liberation. The adult 



