168 



and provided wilh a small, always unariucd opercular valve; the 

 polypide-tube is continued jjroximally beneath the cryptocyst 

 cover Siphonopnrrllii Hincks. 



Steganoporella Sniill. 



I had already studied a series of StcudiioiKirclhi s|)ecies 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 llie species examined by nie. 



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-meml)rane starts from the narrow 

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

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

 or less strongly tuberculous nuuginal portion without pores, which may l)e less 

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

 (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 zocrcium and the 

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

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

 verse ridge, the »oral shell's across the distal wall proximally to the distal margin 

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

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

 is slightly developed in S. neozdanica (fig. .3 a) and quite absent in >S. neozelaiuai, 

 V. magmficn (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 5. 

 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 l)asal 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 lo 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 zocrcium, which is the case in the two upper zoa-cia in fig. 7 d, but some- 

 times the polypide-tube has a basal wall of its own, which is seen in the 1 lower 

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



