32 JOHAN KIÆR. M.-N. Kl. 



1873. Arionellus sp. Th. Kjerulf. Sparagmitfjeldet, Pag. 72, Pag. 83, figs. 7- 9. 



Mentions occurrence-without description of Arionellus sp. and illustrates three 

 specimens. 



1879. Arionellus primaevus Brøgger, Om Paradoxides-skifrene ved Krekling (Nyt Mag. for 

 Naturv. Vol. 24, pag. 58.) 



Describes the form from Tømten without illustrations. 



1887. Arionellus prtniaevus Brogger, G. Holm, Om Olenelltts Kjerulfi. (Geol. Foren. For- 

 handl. Bd. IX, Pag. 22.) 



Mentions Arionellus primaevus Brog. from Tømten with Hohnia Kjerulfi Links. 



Description. This form is very common at Tømten, and in my 

 material there are a great many specimens; unfortunatel}^ only cranidiums 

 were found, these being without the free cheeks, the pygidium entirely missing, 

 and even the thorax extremely rare. Our knowledge of this form is there- 

 fore, — as is the case with all Stremiella forms — very imperfect. 



Cranidium: The majority of the cranidiums present corne from 

 the shales and are therefore all more or less compressed and deformed. The 

 original description was entirely based upon such material. Fortunately I 

 also found some cranidiums in the sandy limestone beds that occur 

 in the Holmia zone. These specimens of course have their original form 

 better preserved, and are therefore of great interest.. As however they 

 are very rare, I will first of all describe the cranidiums from the shales, 

 and then proceed to show in what respects the former differ from the 

 latter. 



Cranidiums preserved in shales. As a whole the cranidium is 

 comparatively flat ; its length is somewhat less than the breadth between 

 the palpebral lobes. The Glabella is markedly arched, comparatively long 

 and narrow (varying however), diminishes in breadth anteriorly, ending 

 somewhat sharply in front, and furnished with 3 pairs of short distinct 

 furrows that are almost equally distant from each other. 



The occipital furrow distinct but narrow. The occipital segment is 

 strongly extented in an arc posteriorly and therefore appears to be very 

 broad. The Glabella is surrounded by distinct and rather deep furrows. 

 The fixed cheeks and the palpebral lobes have about the same breadth as 

 the posterior portion of the glabella and are arched; they have the appea- 

 rance of being pressed upwards on account of the compression of the 

 cranidium in the shales. 



The palpebral lobes commence far back, just near the posterior 

 marginal furrow, and stretch forward in a faint arc until they attain the 

 height of the foremost furrows on the glabella. From that point issue the 

 faintly marked eye brims which are more or less distinct in an arc inwards 

 towards the glabella, without however passing the dorsal furrows. 



