209 



Dance, in which there is a similar relation between areas and zooecia as in M. 

 dubia. Ooecia appear to be found only in B. Elea & B. echinata, and they are 

 here more conspicuous on the surface of the colony than in M. dubia. In the 

 former they appear to have a trilobed opening like the one found in Busk's 

 species. A fossil species, which may also with certainty be referred to this family, 

 is Biflastra Prazaki Novak ^ As the author gives not only a transverse section of 

 a colony but also figures the basal aspect of an isolated zooecial layer we here 

 see a distinct contrast between the broad, rhombic areas and the long, narrow, 

 hexagonal zooecia. Until a closer examination has settled the question whether 

 these species should be referred to one or to several genera we suggest that they 

 be all referred to the genus Membranicellaria. 



Family Cellulariidae ~ (non Hincks). 

 Cellariidae Hincks. 

 Salicornariadae Busk. 

 (Pis. VII & VIII). 



The whole frontal wall of the zocecia is a cryptocyst and they have a well 

 chitinized, bilaminar, simple operculum with a straight or concave proximal 

 margin. Within the proximal and sometimes also within the distal margin of the 

 aperture is placed a pair of (or sometimes a single broad) supporting teeth. 



The oa:cia are hollow spaces in the thick frontal wall and arise by a resorp- 

 tion of the latter, which they finally break through. The subopercular area of 

 the avicularia has an unusually strongly developed, sometimes almost complete 

 cryptocyst. The colonies are most frequently jointed with cylindrical internodes, 

 more seldom two-layered laminae. 



The depressed, rhombic or hexagonal areas are not only separated by the 

 raised borders, in which the more or less sharply ascending lateral parts meet, 

 but also by the distinct furrows which run along the middle of these borders. 

 The aperture surrounded by a somewhat projecting margin is most frequently 

 situated in or proximally to the distal third of the area, more seldom in its 

 centre, and it is most often furnished with a more or less convex, more rarely 

 straight proximal margin, which has generally short, rounded, conical, more 

 seldom long and pointed teeth supporting the operculum. In a few cases a couple 

 of similar teeth are also found in the distal margin of the aperture. The crypto- 

 cyst is more or less tuberculous and in a number of species (for instance in 

 Cell, divaricata. Cell, dubia) it has within each area two long, curved, elevated 



1 85 p. 94, Taf. Ill, figs. 20—25. ' As to the use of the name Cellulariidae see 83, p. 577—78. 



' ' ' ' ' 14 



