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



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

 of a suture-line is visible, but owing to the rough state 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 be observed in the glahella. 



As regards the palaeontological 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 lobation 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- 

 mene. In fact somewhat similar furrows are described by LINDSTROM 

 from a Calymmcne from the Silurian of Gotland (Calymmene excavata 

 LINDSTROM. (Jfversigt, Kgl. Vet.-Ak. Forhandlingar, Vol. 452, Stockholm 

 1885, p. 72, 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 

 Calymmene-Yike, while the head of the Arctic form has no resemblance 

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

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

 under a new genus Frammia, 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 

 "Fram" that thrice carried Norwegian explores on great polar expeditions. 



Thorax and pygidium. The fragmentary thorax with the py- 

 gidium, that is found in the same small piece of limestone as the head 

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

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

 its original position, and is now to be seen close to the posterior part 

 of the thorax with its longitudinal axis nearly at right angles to that 

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

 specimen, and the two parts seem to agree to as to size, state of preser- 

 vation, etc. I think it very probable that the different fragments belong 

 to one specimen. The fact that dorsal furrows, somewhat simular to 

 those that found in the head, are known before just from a Calymmene 

 points towards the same conclusion. 



The posterior, better preserved part of the thorax that has 13 seg- 

 ments show a strongly convex transverse section, the lateral part of 



