24 OLAF HOLTEDAHL, M.-N. Kl. 



Observations. This form does not come very near to any 

 other known to me. In outhne and convexity it resembles the younger 

 Rafinesquina expansa, from which it however differs in surface characters. 

 A rather similar form is the American Raf. alternata var. fracta Meek, 

 specimens of which (from the Maysvillian, Cincinnati; given me by Prof. 

 Schuchert) I have before me. My material of the Norwegian form is, 

 however, too poor for reaching any certain conclusion. 



Occurrence. 4, Cyclocrinus-shale, Furuberget, Mjosen district. 



Rafinesquina sp. 



A small number of ventral valves, all fragmentary, of a rather flat 

 form and very small size (width at hinge about 15 mm.), the one best pre- 

 served having a roundedly deltoid outline. Radiating ribs of two sizes, 

 the major ones in and near the median line being more prominent than in 

 the lateral portions. In this character, and in its flatness it reminds one of 

 the form just described, which, however, is several times as large. 



We here have certainly a new form, but as it is only incompletely 

 known I will refrain from giving it a specific name. 



Occurrence. 4c, Railroad section between Roa and Grindvoll 

 and between Roa and Lunner, Hadeland. 



Rafinesquina, hadelandica n. sp. 



(PI. I, fig. 14) 



Mat. pres. A single, broken ventral valve in rock. 



Description. Shell of rather small size, the total length 17 mm. 

 The exact outline cannot be seen, probably the shell has been relatively 

 long and narrow, with the width not much exceeding the length. Con- 

 vexity moderate and rather even, only the portion around the beak is 

 somewhat distinctly elevated. 



Surface characters can be easily seen : prominent radiating ribs of 

 first order rather strong, increasing in number towards the antero lateral 

 margin by intercalation, and between these stronger ribs, 4 — 7 finer ones 

 (counted in the anterior half of the surface). The radiating ribs in the 

 median portion of the shell are fairly straight, in the postero-lateral portions 

 curving strongly. Under a lens and in a good light, a series of very 

 fine and very crowded concentric raised lines can be seen crossing the 

 radiating ribs. 



Observations. This species to a certain degree resembles small 

 specimens of Raf. alternata, but has a relatively longer outline, different 



