1911] PORTLANDIA ARCTICA GRAY 9 



Lepidopleurus einerens L. was very common, but is only 

 tentatively placed within this group, as it much more probably 

 invaded in the succeeding period, or at least, did not become 

 a leading fossil till then. The two above mentioned species of 

 Boreochiton, on the other hand, only occurred very rarely, but 

 are true inhabitants of the deposits of the age here in question, 

 as they are at present also survivors in the arctic seas. 



Tectura virginea Mull. occurred in numerous specimens 

 measuring 9 mm. This species may also be mentioned as being 

 found in a great many varieties leading into more depressed 

 forms in younger or later deposits. 



Gibbula cineraria L. 

 Gibbula tumida Mont. 



Lacuna divaricata Fabr. was rare, but was found. as well 

 in the more typical form as in the semiglobular one. 



Onoba striata Mont. 

 Rissoa inconspicua Ald. 

 Aporrhais pes pelecani L. .Numerous. 

 Odostomia unidentata Mont. 

 Nassa incrassata Strøm. 



Philine scabra Mull. This species ought perhaps to have 

 been recorded as invading in a former period, but it is tentavively 

 placed under this head. 



Besides these molluscan forms we also meet with some others 

 to be referred to the Spatangidae, Echinidae, Vermes, and 

 Grustaceae. 



Schizaster fragilis Dub. & Kor. was already mentioned 

 in the preceding group, but even if it might have invaded the 

 deep sea-bottom at a somewhat earlier period, it has certainly 

 not become a leading form till the period here dealt with. 



Strongylocentrotus droebachiensis Mull. 

 Echinus esculentus L. 

 Pomatoceros tricuspis Phil. 

 Placostegus politus Sårs. 



