285 



a separable, chitinized operculum, while the somewhat projecting secondary apei'- 

 ture is irregularly circular, sometimes short, transversely oval. Each zoa»cium 

 has about 12 rosetle-plates in its distal hall'. 



The gonozooecia. whicii are considerably larger than the ordinary zoa-cia, 

 are provided with numerous pores, and the primary as well as the secondary 

 aperture is much broader than in the zoa-cia. The proximal margin of the sec- 

 ondary ajjcrture is sometimes almost straight, sometimes rather j)rojecting cen- 

 trally, and it is separated from the large, peristomial pore by a high bridge. 

 They appear everywhere along the margin of the colony on both surfaces and 

 form a belt of up to three longitudinal rows. 



The avicularia occur both as dependent and as independent, of which the 

 latler may be larger than the gonozooecia and especially attain a more consider- 

 able length. They have a well-developed cryptocyst and a long mandible, the 

 two sides of which are sometimes almost parallel and meet in a curve at the 

 end. They api)ear in larger or smaller numbers in the marginal j)ortion of the 

 colony, scattered sometimes singly, sometimes in smaller groups. Within each 

 bifurcation 1 — 5 are always seen, of which the inner one or inner ones always 

 go further inwards on the branch than in the other parts of the colony. The 

 dependent avicularia which are found on the separate zooecia in a number of 

 2 — 3, very seldom 4, are of a rather long, triangular form, and they have the 

 point turned in every possible direction. If 3 are present the two are most often 

 situated on either side of the peristomial pore at the same or nearly the same 

 level, and if there are only 2, the one wanting is most often one of the distals. 

 On the gonozo<jecia the two distal ones are generally situated on either side 

 of the peristomial pore anil have the points turned obliquely inwards and dis- 

 lally. 



The colonies are two-laj'ered, richly branched, bifurcated, with compressed 

 branches, which may attain a breadth of about 4'""' As the daughter-branches 

 behjnging to the same mother-branch never lie at the same level, but are bent 

 more or less strongly in dilVerent dirciiions, the neighbouring branches coalesce 

 in numerous irregular ways. The zod'cia on the separate branches are disposed 

 in oblique, somewhat curved rows and each row terminates in two or sometimes 

 three gonozocL'cia. hi the margin of the colony we find a more or less sliaiply 

 broken row of single individuals, partly kenozooecia of very dilTerent size, whicli 

 may bear a small avicularium, partly independent avicularia, the terminal part 

 of which is strongly projecting, thus giving the branches an irregular, serrated 

 appearance. 



