.">i'< OLAF HOLTEDAHL. [SEC. ARCT. EXP. FH.\M 



behind and to the right of the eye, curving markedly downwards, no trace 

 nf a Mitme-line is visible, hut owing to the rough stale of preservation 

 it is difficult to draw any conclusion as to the real structure. 



Very little surface ornamentation is to be seen, only some faint 

 pustule-like irrregularities may he observed in the glahella. 



As regard- the palaeonlological explanation of the strange furrows 

 described, it seems reasonable to assume that they represent a very 

 peculiar type of dorsal furrow, deepened and widened and combined with 

 a lohation of the margins. 



Very deep dorsal furrows are not seldom met with, and one of the 

 genera that possesses them most conspicuously is the one with which 

 the fragments found with this head show the strongest relation, Calym- 

 nn'Hi'. In fact somewhat similar furrows are described by LINDSTRO.M 

 from a Catymmene from the Silurian of Gotland \Ca1jim-moif excamfa 

 LINDSTRO.M. < )fversigt. Kgl. Vet.-Ak. Forhandlingar, Vol. 4:2, Stockholm 

 1885. p. 1-2. pi. XVI. figs. 14). 



In this form also, lobes are developed at the inner margin of the 

 fixed cheeks. In general appearance, however, the Gotland form is quite 

 Cafa/mwewe-like, while the head of the Arctic form has no resemblance 

 whatever to a Catymmene. It is more like Encrinurus. As it cannot 

 be incorpated into any known genus of Irilobites I propose to place it 

 under a new genus Frttnnnia, characterized by very deep and broad 

 dorsal furrows in the head, diverging towards the front, and with distint 

 lobes at the surface on both sides. The genus is named after the vessel 

 "I 1 ' ram" that thrice carried Norwegian explores on great polar expeditions. 



Thorax and pygidiurn. The fragmentary thorax with the py- 

 gidium. thai is found in the same small piece of limestone as the head 

 jnsl described, in my opinion certainly belongs to the same trilobite 

 .-penmen, of which the head is a part. The head has been moved from 

 its original po-ition, and is now to be seen close to the posterior parl 

 of UK- thorax with its longitudinal axis nearly at right angles to thai 

 of the thorax. As no other trace of Irilobites is found in the rock 

 specimi n, .-iiid the two parts -eeiu to agree to as to si/.e. state of preser- 

 vation, etc. 1 Hunk it very probable that the different fragments belong 

 t' "lie -penmen. The fact that dorsal furrows, somewhat simular to 

 those, thai found in the head, are known before just from a C'tli/ninietie 

 p Is |o\\ards the -anie conclusion. 



'I he po>lenor, heller preserved part of the thorax that has 13 seg- 

 ment- -ho\\ a >ln>ngly convex transverse section, the lateral part of 



