l6 JOHAN KIÆR. M.-N. Kl. 



5. The inner impression of the dorsal valve in the Swedish species 



shows a distinct median furrow, which is not visible in the Norwegian 



specimens. 



As regards the differences here indicated, those given under 2. 3, 

 and 4 are of the greatest importance. Still we ma}- doubt whether they 

 justify a separation. Presumably it would be most correct to regard the 

 Tømten form as a separate species closely related to Obolella Mobergi 

 Walcott. This view is supported by the circumstance that the Swedish 

 variety appears in an older zone. 



Of Walcott's American species of Obolella, O. atlantica appears to 

 approach nearest to our form. It has a fine pedicel tube and a more 

 circular contour, thus agreeing in the latter respect with the Norwegian 

 form. However, the dorsal valve in this case is the more circular, whilst 

 the ventral valve is more pointed. \w the Norwegian variety the case is 

 reversed. Other differences may also occur, and the two forms must thus 

 be kept apart. 



At the same time I must point out that the various species of Obolella 

 that are described and depicted by Walcott in his -monograph, are very 

 closely related to each other, and future revision of the matter will pre- 

 sumably result in several forms being regarded as varieties or local forms 



Obolella (Glyptias) favosa Lnrs. 



1869, Lingula(?) favosa Linnarsson (Öfversigt Kg. Sv. Vet. Ak. Förh. Vol. 26, page 356) 

 Described by Linnarsson from the fucoid sandstone. 



1873. Disctna[l) sp. Kjerulf, Sparagmitfjeldet, page 72, 83, figs. 12 — 13 

 Mentioned and depicted without description. 



1901. Obolella (Glyptias) favosa (Lnrs.) Walcott, Proc. U. S. Nat. Mus., Vol. 33, page 675. 



1912. Obolella (Glyptias) favosa (Lnrs.) Walcott, Cambrian Brachiopoda (Mon. U. S. Geol. 

 Surv., Vol. LL page 600, pi. LV, figs 2, 2 a — d). 

 Described and depicted thoroughly. 



This form was first described by Llnnarsson from the Fucoid sand- 

 stone in Västergötland. It was subsequently minutely described and de- 

 picted by Walcott in his monograph, as a type of the sub. genus Glyptias, 

 that differs essentially from Obolella by the sculpture of the shell only. 

 Walcott's specimens were collected by Sch.malensee at the old Swedish 

 localities. This beautifully sculptured form is not found in my material 

 from Tømten, but as pointed out by Walcott, it is probable that the form 

 depicted by Kjerulf as Discina (?) (from the calcareous sandstone) belongs 

 to this species. It has not been possible to find Kjerulf's original specimen. 



