92 



Family: Aeteidae. 



(PI. VI c, figs. 6 a-6 d). 



The zooecia, which have no spines and the calcareous wall of which is densely 

 covered with pores of different form, consist of two portions inclined towards 

 one another at an angle, the lower of which is as a rule decumhent, adherent, 

 while the upper, mostly tube shaped part is provided at its expanded end with 

 a small membranous frontal area. No cryptocyst. The diaphragm has a structure 

 similar to that in the Ctenostomata. The heterozooecia and ooecia wanting. The 

 distal wall furnished with a row of uniporous rosette-plates. The colony creeping, 

 forming a meshwork of single rows of zooecia, from which free branches some- 

 times issue. 



The partly thin, thread-shaped adherent part, from which the free upright 

 part of the zooecia arises, is by Hi neks compared to a stolon but this name can 

 only be used for a basal portion, consisting of kenozooecia, as found within the 

 order Ctenostomata in the families Vesiculariidae, Triticellidae, Valkeriidae and 

 Mimosellidae and within the Cheilostomata in the genera Chlidonia, Liriozoa and 

 Stirparia. In Aetea the whole colony is built up by autozooecia, and the fact, 

 that the proximal part of the zocEcium is thin and much elongated, does not 

 entitle us to speak of a stolon in these species any more than in the species, 

 which Hincks refers to the genus Hippothoa. The adherent parts of two successive 

 zooecia are separated by a wall, which in Aetea dilatata is furnished with a row 

 of 7 unipoi'ous rosette-plates, and a similar separating wall is found everywhere, 

 where one zooecium issues from another. In Aetea truncata according to Hincks 

 new free zooecia may issue from the basal side of the ascending part of the 

 zooecium. The calcareous wall of the zooecium is richly furnished with pores,, 

 which in different species can appear in different ways. Thus, while the whole 

 calcareous surface in Aetea dilatata is furnished with round pores, the form of 

 the pores varies in many other species at different places. For example, the distal 

 part of the zooecium in Aetea angiiina and also the broadest part of the adherent 

 portion are furnished with small round or oval pores. In the narrower part of 

 the adherent portion they fuse together to longer, slit-like spots (fig. 6 d), and 

 in the largest part of the ascending portion (fig. 6 c) they become continuous, 

 ring-shaped interruptions, and therefore the calcareous portions appear as a row 

 of free rings situated above each other, which can be isolated without great diffi- 

 culty. Sometimes however we find a short connecting branch between two succes- 

 sive rings, or a bifurcation of a single ring. Waters* has found an egg enclosed 



' 111, p. 5, PI. I, figs. 1—5. 



