1915- No. 12. THE STROPHOMENinAE OF THE KRISTIANIA REGION. 23 



anterior frontal margin is deflected, but as the frontal poition of the shell 

 is never well-preserved the width (height) of the deflected rim cannot be 

 exactU' fixed. It seems, however, to be narrow compared with the rest 

 of the shell. The ventral posterior part of the shell is only very slightly' 

 convex in the longitudinal direction, in transverse section more so, the 

 median part forming a low ridge-like elevation, from which the surface 

 slopes to both sides. The dorsal valve has a form similar to the ventral, 

 with the exception that the central disc here is flat. 



The surface markings consist of rather fine, crowded, radiating ribs, 

 all of practically the same size, except for a few near the median line 

 that are somewhat more prominent than the rest. The number of ribs 

 increases greati}- (by bifurcation generally) towards the antero-lateral margin. 



Observations. Li spite of the material that is at hand of this 

 form being v^ery poor, I think it is well enough known to be named. 

 With its small size and peculiar striation, with ribs of uniform size, ii is 

 a rather characteristic species. The Rafinesqiiina mjosetisis from higher 

 beds described above shows a good deal of similarity in the outer form, 

 but is distinctly larger and has a different surface marking. 



Occurrence. 4, Cj'clocrinus-shale, Furuberget. Mjosen district. 



Eaßnesquina sp. 

 iPI. I. fig. 15.) 



Mat. pres, .\ single and incomplete ventral valve, besides minor 

 fragments. 



Description. Shell of medium size (see figurel, outline semi- 

 elliptical, cardinal extremities not preserved, have probably only been 

 slightly prominent. Convexity very moderate, most marked around the 

 elevated umbonal region, gradually becoming very slightly defined an- 

 teriorly and laterally. 



The surface ornamentation of the shell is very typical. Usually we 

 have radiating ribs of two orders, however, not very regularly arranged, 

 sometimes two stronger striae are separated by only one inferior rib, 

 sometimes by a larger number. In the median portion of the valve the 

 size of the ribs are greatly increased, not onh* the main ribs but also 

 those between, the latter becoming as prominent as the major striae in the 

 lateral parts of the shell. At a distance from the hinge of V3 of the total 

 length of the valve, we observe three major ribs of especial prominence, 

 the number becoming larger towards the front. In places where the pre- 

 servation of the surtace is good, very fine, crowded, raised, concentric 

 lines can be seen. 



