127 



the colony is strongly dichotomously branched with generally the branches con- 

 nected so as to form an open network. Radical fibres arise from the marginal 

 belt consisting of kenozooecia in the approximal corners of the angles of the 

 branches. 



It is possible that we may be able to add to this diagnosis still one or more 

 characters, taken from the structure of the auicularia ; but for the present I only 

 know the structure of the avicularia in the new species R. Schonaui. 



R. Schonaui n. sp. 



(PI. I, figs. 7 a-7 d). 



The zooecia are of somewhat variable form, in most cases elongated, rect- 

 angularly oval, with a distal curved margin, often a little irregular, especially in 

 the marginal portion of the branches. There is a more strongly developed crypto- 

 cyst than in any other member of tlie family. It appears as a marginal region 

 along the whole extent of the zooecium and shows distinct belts of growth; these 

 are specially obvious in the strongly developed proximal region. The larger part 

 of the basal wall of the zooecium is uncalcified and has an oval form (fig. 7 d), 

 only a belt along each side and a larger or smaller (Vsth — ^Ui'd) proximal por- 

 tion being calcified. Owing to the slight strength of the calcification this oval 

 only becomes distinct after it has been boiled in potash and only with reduced 

 light. The calcareous part of the basal wall of the zooecium, and especially its 

 proximal part, shows occasionally a number of transversely or obliquely placed 

 coarse strije. 



The distal wall, which is angularly bent and saddle-shaped in the direction 

 from front to back, is furnished, with a transverse row of 6 — <S uniporous rosette- 

 j)lates, while the distal half of each side-wall has 2 — 4. Partly owing to the 

 saddle-shaped curvature of the distal wall, partly because the basal edge is placed 

 higher than the frontal, we can see a large part of the under side of the distal 

 wall from the basal aspect of the colony. The branches are everywhere bordered 

 by a narrow marginal region, which here and there shows an inner separating 

 wall, and must be regarded as formed by kenozooecia. It is only at the point 

 where the branches bifurcate, consequently at the two ends of the oval perfora- 

 tions, that this region has a larger extent and shows basally a gymnocyst and 

 on the frontal side a cryptocyst with belts of growth. Here and there a radical 

 fibre issues from the approximal corner of such a perforation. 



The avicularia (iig. 7 a) are very rare, and I have altogether only seen two. 

 They are of the same size as the zooecia, pointed proximally and almost pear- 

 shaped. Contrary to the rule in Malacostega, they are far proximally provided 



