271 



bearing zooecia. In the former it springs from the lateral surface of the zooecium 

 close to the zigzag ridge and at a fairly great distance from the distal wall, and 

 in the latter it stai'ts from the approximate centre of the proximal part of the 

 frontal surface. In both cases it ends in the above-mentioned, collar-shaped part 

 at the base of the ooecium. To keep the covering-membrane extended there is 

 further a very small, flat, most often trapeziform process situated on each side 

 of the aperture. This process Busk wrongly takes to be an avicularium (figs, 

 la, If). 



Along the fi-ontal margin of the abramal zigzag ridge we find on each zooe- 

 cium a longitudinal row of 5 — 7 small, widely separated, uniporous rosette-plates, 

 and similar rosette-plates appear on both sides of the adramal arch-shaped ridges. 

 Along the frontal margin of the ridge there are 6 — 8, while those on the other 

 side of the ridge are more varying in number (3 — 7), and may sometimes be 

 rather irregularly scattered. Finally each of the two frontal rows of rosette-plates 

 is continued into a row or group of 4 — 8 plates situated on each side of the 

 aperture. 



The obliquely ascending distal wall has a basal trilobed margin and is pro- 

 vided with numerous, uniporous rosette-plates, which are scattered over its entire 

 surface, and such plates appear also in a longitudinal belt or row, which passes 

 through the whole centre of the basal surface (fig. 1 d). 



The obliquely truncated aperture, which forms an obtuse angle with the fron- 

 tal surface, has a semi-circular anter, while its poster is provided with a well- 

 developed rounded sinus. The slightly chitinized operculum, which is of a 

 corresponding form, has a somewhat curved, transverse row of round, bright 

 spots. 



The ooecia are of a most peculiar structure, being endozooecial and at the 

 same time having their endoocecium situated frontally to the cryptocyst of Ihe 

 zooecium, which is much excavated to receive its strongly arched basal surface. 

 There is a transparent ectoooecium, formed by the covering membrane, and a 

 calcified, radiately striated endoocecium, which is somewhat narrowed at the base 

 in the shape of a neck, and the form of which is that of a Phrygian cap rounded 

 at the end. A large part of the frontal surface of the endoocecium is provided 

 with numerous, round, attenuated spots. The distal wall belonging to the ocEcium 

 has rosette-plates not only in its basal trilobed part but also in the narrow part 

 bounding the ooecium on either side. Finally, it may also be remarked that the 

 ooecium can be closed by the operculum of the zooecium. 



The colonies are richly branched, bifurcated tufts with compressed branches 



