34 OLAF HOLTEDAHL. M.-N. Kl. 



Convexity rather marked, with rounded geniculation at about the 

 middle of the length of the shell. 



Surface markings consisting of delicate radiating striae of two distinct 

 sizes, the stronger ones with very little distance (in the specimen with 

 best preserved surface, on a average ^/3 mm.) und usually with 3—4 of 

 the very fine intervening striæ between each two. Very delicate, crowded, 

 concentric lines are present, but no corrugations. 



In a few specimens, the posterior part of the ventral muscular 

 area can indistinctly be seen in the mould, the margins meeting at the 

 hinge at an angle of about 75°. 



. Observations. Though the material is rather scanty it seems to 

 be beyond doubt that we have here a typical little form with fixed 

 characters, a form well distinguished by small size, comparatively great 

 width and great convexity, delicate radiating striæ of two sizes, with com- 

 paratively small intervals between each two of the stronger ones. The 

 form certainly comes exceedingly near to Strophomena pseiideuglypha Gagel 

 (see »Brachiopoden der cambr. u. sil. Geschiebe im Diluvium der Provinzen 

 Ost- und Westpreufeens« ^ p. 45, pl. III, fig. 16). Form and size seem 

 to be exactly equal, whilst in the surface markings to judge from Gagels 

 description and illustration there is a slight difference. Gagel states: 

 »Oberfläche mit zahlreichen mittelfeinen, scharfen Rippen bedeckt, deren 

 breite Zwischenräume von einer wechselnden Anzahl feinerer Radial- 

 streifen ausgefüllt werden«. Also in bis illustration the relatively large 

 distance between each two of the rather prominent main ribs is distinctly 

 marked. In the Norwegian specimens as stated above the said distance is 

 extremely small. This distinguishing feature is certainly of no great syste-. 

 matic value and further studies with larger material may prove it to be 

 worth still less. The form is externally like the British Llandovery species 

 Strophomena areuacea Salt., but has not the peculiar interior features of 

 the latter. 



Occurrence. 6, Limaastangen, Ringerike (6 c); Enger vand. 

 Asker— Bærum; Sommerfryd, Skien— Langesund 

 district. 

 7, Bjerkø ofif Holmestrand (7 a) ; Malmø, Bunde- 

 fjord (7 b). 



1 Beiträge zur Naturkunde PreuÊens. 6. 1890. 



