﻿712 SUMMARY OF THE CONTENTS. 



In the littoral zone (above 30 fathoms) in the Kristiania 



Fjord, only 241 species (29 a, 107 b, 105 1.) are known (see p. 

 579). We thus have 



Are. Bor. Lus. Total 



Postglacial mollusca of the Kristiania region . 40 103 112 255 

 Living moll. of the Kristiania Fjord (above 30 



fath.) 29 107 105 241 



Species common to the postgl. and living fauna 26 94 90 210 



Pp. 581 — 594. The Species of Mollusca from Postglacial 

 Deposits, not known living in the Kristiania Fjord. 



This chapter contains a discussion of the postglacial species 

 become extinct in the Kristiania Fjord in recent times, especially 

 the lusitanic species {pholas candida, tapes decussatus^ tellina 

 crassa, area tetragona, cardium tuherculatum, lepton squa- 

 mosum, scrohicularia piperata, lasæa ruhra, macoma fabula, 

 psammobia vespertina, solecurtus antiquatus, and a series of 

 small species enumerated on pp. 588 and 589). A number of 

 other species, emong them isocardia cor (pp. 589, 590) common 

 in the fjord in postglacial times are now very rare, others un- 

 doubtedly more rare than in postglacial times (see pp. 591, 592). 

 The common oyster [ostræa edulis) is also among these species 

 (pp. 592, 594). 



Pp. 594 — 614. Recent Species, hitherto Unknown in the 

 Postglacial Deposits. 



On pp. 594—601, several arctic species {acmæa testudi- 

 nalis, lophyrus albus, scalaria grønlandica, cerithiopsis 

 costulata and nucula delphinodonta are mentioned, their di- 

 stribution being characterised by their absence from the polar 

 sea N. of Asia, the Kara sea, etc, while they are known both 

 living and (partly) fossil i the nearctic area. Emphazis is laid 

 on the hypothesis that these species have perhaps immigrated 

 in recent times from the northern part of the American conti- 

 nent to the Scandinavian peninsula. 



