52 



OLAF HOLTEDAHL. M.-N. Kl. 



abruptly anteriorly. In front, the border of the muscular area is not 

 distinctly marked. In the median portion two short faint, parallel longi- 

 tudinal ridges have existed; farther towards the front, there was only one. 

 In the dorsal mould can be seen two very small, but rather deep cavities, 

 corresponding to the branches of the bilobate cardinal process. From the 

 basal part of the cardinal process the delicate crural plates curved, first 

 towards the front, then again approaching the hinge line, the lateral 

 portions, that gradually become less and less prominent, running almost 

 parallel to the hinge line. 



Occurrence. 4b (transition 4 b a — 4 b ß), Bratterud, Ringerike. 



Coelosphæridium zone, Mjøsen district. 



Among the very fragmentary material of S. Asniusi from Coelosphæ- 

 ridium and Cyclocrinus horizons of the Mjosen district are found a few 

 more complete specimens (however very fragmentary) that show a remark- 

 ably long and narrow outline as will be seen in pi. VIII, fig. 4 — 5, — an 

 outline that I do not think is due to deformation by pressure. The sur- 

 face ornamentation is like that in the above mentioned specimens, perhaps 

 a little less regular, and with smaller intervals between the major ribs. 



It may be that we have here a constant type, varying a little from 

 the typical S. Asmnsi, by a more elongate outline. With such poor 

 material, however, the question cannot be decided. 



Occurrence. Coelosphaeridiumzone. Fangberget. Mjesen district. 



Specimens are present also from 4 b Hadeland, 4 b Skien-Langesund 

 district and 4 d Ringerike, but as the material is rather poor, I will not go 

 into details. They do not seem to diff"er in any essential characters from 

 the broader types of 5. Asmusi from Hadeland and Ringerike. 



4 c. Hadeland. (PI. VIII, fig. 6.) 



A number of ventral and dorsal valves in rock show a very large 

 similarity to the specimens first described. Size, outline and surface 

 markings are entirely alike. The only distinguishing feature is a more 

 pronounced convexity in dorsal valves, as will be seen from the illu- 

 stration. The cavities corresponding to the crural plates can be well 

 seen in the specimen depicted, and have exactly the same character as 

 in the specimens from 4 b, Ringerike. 



Occurrence. 4c (in beds of sandy limestone, probably corre- 

 sponding to the lower Cyclocrinus horizon of the Mjesen district), Shore 

 of the Randsfjord, South of Reikenvik, and Haugslandet, Hadeland. 



