34 OLAF HOLTEDAHL. [SEC. ARCT. EXP. FRAM 



The pygidium upon which this species is based differs distinctly by its 

 narrower marginal rim. 



Occurrence: B, upper part, over the fragment-limestone, Valley 

 south of Borgen. 



Encrinuridae. 



Encrinurus EMMERICH. 



Encrinurus sp. 



PI. VIII, fig. 13. 



A badly preserved fragment of a trilobite-pygidium indicates this 

 genus. The form of the pygidium is a very elongated triangle, the sur- 

 face in transverse section moderately convex. The axis is prominent, 

 with a strong tubercle on each segment. As the lower part is strongly 

 weathered the number of the segments cannot be discerned. On the left 

 lateral portion about 8 pleural lobes can be counted, corresponding to the 

 same number of segments on the axis, all with one or more tubercles. 

 In outline and number of segments and pleura the pygidium comes near 

 to Encrinurus (Cromus) transiens BARR* from Etage E. This form 

 differs, however, by having many tubercles of equal strength on each 

 segment of the axis. 



On another piece of limestone from the same locality and of exactly 

 the same lithological character as the one in which the pygidium was 

 found, occurs a very small fragment of what I think is the head of the 

 same Enccinurus sp. It shows only the marginal part of the left half 

 of the head, from the middle of the glabella and half down the free 

 cheek, strongly ornamented with big round tubercles. 



Occurrence: B, lower part, Reindeer Valley. 



Encrinurus (?) sp. 



Another weathered pygidium of broader triangular outline may 

 probably also be referred to Encrinurus. The number of the axial seg- 

 ments is about 13, that of the pleural lobes 1011. The marginal part 

 of the pleura is greatly curved downwards throughout. There appear to 

 have been tubercles present on the surface, but they are now worn away. 



Occurrence: B, lower part, Reindeer Valley. 



1 Syst. Sil., Trilobites, p. 828, pi. 43, figs. 18-19. 



