168 



and provided with a small, always unarmed opercular valve; the 

 polypide-tube is continued proximally beneath the cryptocyst 

 cover Siphonoporella Hincks. 



Steganoporella Smitt. 



I had already studied a series of Steganoporella species and prepared the 

 figures given on PI. V, when I received Harmer's excellent monography of this 

 genus. Accordingly 1 shall here only make a number of observations on the 

 structure of this genus, especially with regard to the species examined by me. 



While the operculum is in most species surrounded distally and laterally by 

 a projecting margin formed by the gymnocyst, the whole of the remaining calci- 

 fied frontal wall is a cryptocyst, as the covering-membrane starts from the narrow 

 frontal edges of the lateral walls. Besides the polypide-tube the cryptocyst shows 

 a distinction between a depressed central portion with pores and a raised, more 

 or less strongly tuberculous marginal portion without pores, which may be less 

 distinct in the proximal part of the zooecium. In some species, e. g. in S. lateralis 

 (PI. V, figs. 7 a — 7 d) we also find such a raised, non-porous, tuberculous portion 

 immediately on the proximal side of the aperture of the zooecium and the 

 polypide-tube. In most species the lateral, raised marginal portion of the crypto- 

 cyst is continued distaUy between the hinge-teeth and forms an arched trans- 

 verse ridge, the »oral shelf «, across the distal wall proximally to the distal margin 

 of the opening. This distal cryptocyst, which springs from tlie angle between the 

 basal, more horizontal and the frontal, more ascending part of the distal wall, 

 is slightly developed in S. neozelanica (fig. 3 a) and quite absent in S. neozelanica, 

 V. magnifica (fig. 4 a) and in S. lateralis (figs. 7 a, 7 b). While in all the other 

 species the »opesiular outgrowths*; terminate on the basal wall, they end in S. 

 haddoni Harmer and S. Buski Harmer (figs. 6 a— 6 c) on the distal wall, which 

 accordingly in both these species forms the basal wall of the polypide-tube. The 

 way in which these outgrowths join the basal wall in the species examined by 

 me or, what comes to the same thing, the way in which the basal wall of the 

 polypide-tube is formed, seems however to be subject to rather great variation 

 within the same species or even within the same colony. This is easily seen 

 through the basal surface of the colony, the lines in which the outgrowths join 

 the latter being visible. In St. magnilabris as well as in St. lateralis Harmer the 

 basal wall of the polypide-tube may sometimes be formed by the basal surface 

 of the zooecium, which is the case in the two upper zooecia in fig. 7 d, but some- 

 times the polypide-tube has a basal wall of its own, which is seen in the 4 lower 

 zooecia jn the same figure. In the piece of St. magnilabris represented in fig. 5 b 



