301 



inserted between the membranous ectoooecium and the calcified endoooecium. 

 From Waters' statement ^ regarding this ooecium: »I propose to call this a con- 

 cealed ovicell, retaining the expression immersed for those which give an external 

 indication of their presences one would conclude that the ooecia in the specimen 

 examined by Waters were not distinctly seen on the surface of the colony. 



Avicularia. The peristomial arch is on each side provided with a large, robust, 

 triangular, obliquely ascending avicularium, and the broad, trapeziform proximal 

 part of the mandible grades over into an elongated part, the two, almost parallel 

 lateral edges of which finally run together in a stout terminal hook. 



Of this species I have examined several colonies with labyrinthine-like branch- 

 ings and round or compressed, two-layered branches from the Cape and Port 

 Elizabeth. 



To the genus Myriozoum belong the species M. truncatum, M. coarctatum, M. sab- 

 gracile and probably also the species described by Busk,^ M. honolulense, M. 

 simplex and M. marionense, in the last of which the ooecial cover only reaches 

 halfway down over the frontal surface of the ocEcium. To this genus I must also 

 refer the two-layered, laminate »Escharoides'^ occlusa Busk^ and the one-layered 

 ^Schizoporella<i biturrita Hincks,* which shows several points of agreement with 

 Gephyrophora polymorpha. The genus Myriozoella is only represented by a single 

 species, the incrusting M. Crustacea Smitt. 



Family Sclerodomidae n. f. 



The zooecia, which have a covering membrane but no spines, are very thick- 

 walled and consist of a very solid and hard, finely striated calcareous mass, which 

 is perforated by pore-canals, sometimes scattered, sometimes arranged within the 

 lateral margins. The very small distal wall is provided with a number of uni- 

 porous rosette plates and the lateral walls with a varying number of rosette-plates 

 with few (2 — 3) pores. There is a membranous or weakly chitinized operculum 

 and a more or less well-developed peristome. Dependent avicularia are present and 

 are frequently situated within or outside the peristome. The hyperstomial ocecia, 

 which have a membranous ectoooecium, are only distinct on the surface of the 

 colony in quite the youngest zooecia, as they are quickly covered over by a 

 thickened layer or by the peristome. The colonies are free, branched. 



Genera. 



The peristome is funnel-shaped, immersed, not projecting, provided 

 with avicularia; no peristomial pore; in the ooecium-bearing zooecia 



1 110, p. 29-30, PI. II, figs. 21—24. ' 8, p. 170. ' 110, p. 26. * 29, p. 280. 



