330 



fibres, which arise from the pore-chambers in the outer walls of the marginal 

 zooecia, some of which have no aperture. At the beginning of the older bifurca- 

 tions a bundle of radical fibres stretches obliquely across over the surface of a 

 bifurcation to attach itself to the opposite margin of this, and this may some- 

 times occur on both surfaces at the same time. Each of these radical fibres 

 (fig. 3e) is provided with two longitudinal rows of large, multiporous rosette- 

 plates, each of which is surrounded by a calcified ring formed originally by a 

 number of small pieces separated by sutures. Sooner or later, however, all these 

 calcareous rings become connected with each other. Further, other radical fibres 

 also occur in a very peculiar manner, as they everywhere surround the single 

 zooecia and cover the sutural lines between these. The two layers of zooecia, of 

 which the colony consists, are connected with one another in such a way, that 

 a longitudinal row of zooecia in the one layer corresponds to a longitudinal row 

 in the opposite layer; but the zooecia in two such opposite longitudinal rows 

 alternate and each zooecium is connected with two zooecia in the opposite row. 

 This is seen amongst other things from the manner in which the rosette-plates 

 and openings of the basal walls are arranged. 



Of this species I have examined two colonies from South Australia (Miss 

 Jelly. Dr. Holub). 



Microporella flabellaris Busk. 



Eschara flabellaris Busk, Catalogue of Marine Polyzoa, Cheilostomata, 



p. 91, PI. CVII, figs. 7—10. 



(PI. XV, figs. 4 a— f). 



The zooecia rounded hexagonal, fairly strongly arched, tuberculated and pro- 

 vided with numerous scattered pores. The aperture is broader than long and 

 provided with a somewhat projecting anter, the proximally converging, generally 

 concave lateral margins of which sometimes grade directly over into the distal 

 margin and are sometimes marked off from this by a more or less distinct angle. 

 The supporting beam is well-developed with a more or less distinct, dentated 

 edge, but without special lateral teeth. The operculum, which is well-chitinized 

 with a marginal thickening on the anter, is provided with a faintly convex proxi- 

 mal margin, which on each side has a small, rounded thickening for a muscular 

 attachment. The narrow ascopore, which has toothed margins, is broader than 

 long and there is sometimes a tuberculated projection proximally to it. Each 

 distal wall is provided with 2 — 3 multiporous pore-chambers. Whilst the distal 

 lateral wall, which is opposite the vibraculum, is provided with a multiporous 

 rosette-plate, the other distal lateral wall has a pore-chamber and this abuts upon 



