40 OLAF HOLTEDAHL. M.-N. Kl. 



end about 3 mm. from the hinge. The whole character of the muscular 

 field seems to be very much like that found in Brachyprion seiniglobosum 

 var. norvegicum. 



In a dorsal valve the bilobed cardinal process can be nicely seen. 

 The two, in cross section well rounded branches have a greatest length 

 of somewhat more than i mm. and diverge at about 60°. In front of the 

 cardinal process are indicated three faint longitudinal ridges, a median one, 

 the length of which is nearly half the length of the valve, and further 

 one, — a little shorter, — on each side, the distance between the two 

 lateral ones at their frontal end about 672 mm. 



Observations. When compared with specimens from Gotland 

 (from which B. Wahnstcdti was first described) the more evenly globose 

 Norwegian specimens show a full similarity, the Swedish specimens also 

 showing a good deal of difference as to the degree of the convexity. Of 

 the 8 Gotland specimen that I have before me, not a single one, however, 

 has any indication of the longitudinal keel-like elevation seen in more than 

 half of the Norwegian ones. But as mentioned above, we have transitional 

 stages, so the »keeled« Norwegian type cannot be considered as a distinct 

 and permanent variety. Davidson's figure in his monograph, pi. XL, fig. 6 

 shows a faint longitudinal elevation. 



Occurrence. 7c —8 c, Loc. in Hadeland, Ringerike, Skien-Lange- 

 sund district. 



Subgenus Leptostrophia Hall and Clarke, 1892. 



Under the genus Strophcodonla Hall, Hall and Clarke in the »Intro- 

 duction to the Study of the Genera of Palæozoic fossil Brachiopoda«, 

 p. 287 — 288 mention a group of Stropheodontas that differs distinctly from 

 the ordinary concavo-convex specimens (type species S. demissa Conrad) 

 by being nearly flat, by a very fine surface striation, as well as by certain 

 interior characters. For that group is proposed the term Lcptostrophia. 

 The majority of these forms occur in the Devonic, but Siluric represen- 

 tatives are also found, thus there is mentioned Strophomcna filosa Sow. 

 from the British Wenlock. 



Leptostrophia cf. filosa Sow. 

 (PI. II, fig. 14.) 

 Mat. pres. A number of very fragmentar}- ventral and outer 

 moulds of dorsal valves in rock. 



Description. Exact outline not known. Judging from the frag- 

 ments, however, it is certainly rather broad, width probably nearly double 



