20 0. NORDGAARD. [2nd arc. exp. fram 



was nearly oval, but was also sometimes of a shape that somewhat re- 

 called Schizoporella sinuosa. There were no avicularia to be seen. 

 The ooecia, which were of extremely rare occurrence, were almost as 

 broad as they were long. There was an indication of a median pore, 

 from which a hne or suture ran to the margin of the oral aperture; 

 but with this exceptions there were neither hollows nor perforations 

 (fig. 23). The operculum (fig. 24) was furnished with a lobe, which 

 was bent to one side. When the flap of the operculum is lying horizon- 

 tally, only the projection of this lobe is seen. 



I have taken the liberty of calling this species after Hr. Olaf Biden- 

 KAP, formerly curator at the Tromso Museum. 



Upon an examination of the above species, I was induced to look 

 through my specimens of Schizoporella sinuosa, Busk. It then appeared 

 inter alia, that this species also had an opercular lobe that was bent 

 to one side, which in many cases gives it the appearance of a thicken- 

 ing of a lower margin. For this very reason, I have apprehended and 

 drawn the operculum inaccurately in an earlier work '. It proved also, 

 that the form from Herlo Sound near Bergen, which I had taken to be 

 (S. sinuosa, diferred not a httle from the one I had taken in the Trond- 

 hjem Fjord and in the north of Norway. They ought at any rate to be 

 distinguished from one another as varieties; in reality, I think they 

 ought to be considered as independent species. 



On Modiola modiolus from Herlo Sound, not far from Bergen, I 

 have a Schizoporella which, in a living state, formed a yellow incru- 

 station, which when dried, assumed a bright reddish brown colour. In 

 the frontal wall of the zooecia there were large pores, of which those on 

 the margin were larger than the others (fig. 25). The ooecia had a large 

 median pore; and the width of the opercular lobe amounted to about 

 half the width of the operculum (fig. 27). The interzooecial pore tubes 

 exhibited an arrangement that is usual in the genus Schizoporella; there 

 were two terminal pore-chambers (fig. 26). 



It is probable that fig. 5 (PI. XLII in Brit. Mar. Pol.) is meant for 

 this form; and it is also almost certain that ttiis is what Levinsen 

 {Fauna danica) calls Schizoporella sinuosa. 



In the specimens from the north of Norway, the zooecia were lar- 

 ger and the frontal perforation closer than in colonies from Herlo Sound 

 (fig. 31). But the marginal pores differed here too from the others. 

 The oral aperture was of the same shape in both; but on the colonies 



Hydr. Biol. Inv. Norw. Fj., p. 1G5, PI. 3, fig. 10. 



