1915- No. 12. THE STROPHOMENIDA F. OF THE KRISTIANIA REGION. 



105 



Lime- 



sume 



Shalt 



Limestone 



and shale 



Strophoniena Loz-eni V^erx 



— Sœfieldi W. a. S 



— sp 



Amphistrophia Davidsoni n. nom 



— fuglyphoidcs n.sp 



Strophonella euglvpha His 



Schuchertclla pecten Dalm 



Leptaeiia rhotttbotdalis Wilck 



— Kjerttlfi n. sp 



— cf. uniœstata Meek and Worthen 



— sp. tcf. Hniœstaia\ 



— undata M'Coy ? 



Plectaitibomtes (?) Kristianiae n. sp 



Pkcla»iboni/es cf. papillosa Ccmp. Reed 



— coHve.xa Paxd 



— qiiinquecostata M'CoY 



— cf. quhiquecostaia M'CoY 



— trabeata Lindstr. var. nrimiinata n. var. . 



— sp 



— sericea Sow. var. rhotnbica M'CoY 



— sericea Sow 



— Schmidti TöRNQ. var. precedeus, n. var. . 



— Schtnidti TÖRXO 



— traitsversalis Dalm 



— scissa Salt. var. triangularis n. var. 



Christiania ienuicincta M'Cov 



TripUcia ittsularis EiCH 



— insularis Eich. var. anticostietisis Twexhofel 

 Strepiis tnonilijera M'Coy var. altosinuata n. var. . . . 



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49 



Of the forms found in both limestone and shale many occur preemi- 

 nently in one of the two types of sediment, being generally most common 

 in limestone. A form that is found by far in greatest number and also 

 largest specimens in shale (4 b ft) is Christiania tcnuicincta. The largest 

 specimens also of Pint, traitsversalis are found in shale (of stage 6). 



Though in general a clear salt water and a very moderate depth (arena- 

 ceous limestones are often exeedingly rich in Strophonienids) have given 

 the fossils here treated the most favorable biological conditions, they have 



