108 SIDNEY F. HAEMER. 



wards or obliquely upwards^ the ooeciopore being conspicuously 

 larger than an orifice. Its tube is recumbent on a series of 

 zooecia, and does not often become completely free, as is nor- 

 mally the case in T. aperta. The shape of the ooeciopore is 

 usually complicated by a slight fold or indentation of one side, 

 as shown in fig. 1, or of both sides. The size of the ooeciopore 

 varies from 270 fx to 430 fx, the average being 355 ju. 



T. plum OS a reaches its largest size in the cavities of the 

 bulb-like bases of Laminaria (Saccorhiza) bulbosa. One 

 of the finest colonies I have seen was approximately circular, 

 with a diameter of 21 mm., and its peripheral parts were 

 formed of sixteen separate lobes, some of them bifurcated. 

 These colonies are attached to the seaweed by remarkable 

 ridges on their under side,^ similar to those which have been 

 figured by Waters (44, pi, vii, figs. 2, 3) in an Australian form, 

 termed by him T, fimbria, forma pulchra, MacG., and by 

 Busk (3, pi. V, fig. l.b) in T. '^ flabellaris.'' The ridges do 

 not project greatly, and their general arrangement is radially 

 dichotomous. As the colony increases in diameter, the ridges 

 increase in length, often dividing or undergoing a cessation of 

 growth. When the ridge is re-formed it commonly grows in 

 such a way as to prolong the direction of its more proximal 

 portion. In one case a ridge was observed measuring 1"36 mm. 

 without interruption, but the ridges are usually much shorter 

 than this. If the ridge is narrow its axis may be occupied by 

 a single row of pores, which correspond with the ordinary 

 zooecial pores, but are considerably larger. If the ridge is 

 broader the number of rows of pores is correspondingly in- 

 creased, and large areas of the lower side are sometimes in 

 the form of broad, irregular, porous areas, which radiate out 

 into narrower ridges towards the distal part of the colony. 

 In some cases the ridges are broken up into short pieces, only 

 large enough to contain a few pores, sometimes only a single 

 pore. If the base of the colony is, by reason of an irregularity 

 in the surface of the seaweed or for any other cause, separated 



' The colonies can be conveniently removed from the seaweed by prolonged 

 boiling with caustic potash. 



