139 



each side of the proximal pari of the aperture distally to the cryptocyst (figs. 

 7 b — 7 c). The basal, horizontal part of the distal wall has a transversely oval or 

 triangularly rounded, multiporous rosette-plate, generally with a frontal concavity 

 (figs. 7 f, 7 h). In most zooecia the distal wall between the rosette-plate and the 

 basal wall is provided with a little rounded (sometimes two) pore-chamber de- 

 scending into the lower zocecium (figs. 7 d — 7 e) and in its bottom furnished 

 with one or more small uniporous rosette-plates. 



The avicularia occur in two different forms of which one is found in the 

 cavity of the zorecium, while the other in zooecia without oa?cium is found on the 

 proximal side of the membranous area, and in ooecia-bearing zooecia on each 

 side of the distal part of the ocecium. The external avicularium, which has a 

 well-developed hook as well on the mandible as on the corresponding part of 

 the chamber, is placed so, that the mandible is turned obliquely outwards and 

 distally on the ofrcia and obliquely inwards and proximally on the zooecia. The 

 boundary between the opercular and the subopercular area is formed by two 

 nearly always concurrent, narrow, cylindrical, generally bent and often very ir- 

 regular processes, of which one is usually longer than the other (figs. 7 c, 7 i). 

 On the proximal side of the frontal area we find very seldom two, generally but 

 a single avicularium which is then most often situated on the outer side (the 

 one nearest the margin of the colony) and occupying more than half the space. 

 If found on the marginal zooecia it is however placed On the inner side, the 

 reason of which may l)e, that there is a large pore-chamber on the outer side, 

 from which a radical fibre takes its origin. In the ordinary zooecia, at the proxi- 

 mal end of which there is but a single external avicularium, and in the marginal 

 zooecia with no external avicularium, an internal one is always found, arising 

 from the internal side of the surface which from its position seems intended to 

 have an external avicularium. The latter, which has both a mandibular and an 

 avicularian hook, is oval, with the mandible pointing obliquely distally and in- 

 wards, and with but two short teeth on the boundary between the opercular and 

 the subopercular area (figs. 7 d, 7 e, 7 g, 7 k). 



The ooecia are rather high, rounded and the ectoooccium has a proximal, 

 rounded triangular, membranous area, while its calcified part terminates in a 

 somewhat projecting, angularly bent margin. 



The colonies are bilaminate, dichotomously branched and their branches 

 have up to Hi rows of zooecia. A bundle of radical fibres springing from the 

 pore-chambers in the proximal part of the marginal zooecia runs along each 

 lateral margin. 



