JOHAN KIÆR. M.-N. Kl. 



to the Scandinavian genera Holuiia and Kjcrulfm than to the American 

 genus Mcsonacis. 



The latter is characterized according to Walcott especially by the 

 unique structure of the thoracic segments. The number of the latter is very 

 large, in the case of the geno-t^-pe Mes. Veruioutaua Mall 25. As in 

 Pacdcumias and Oleiicllus the third is strengthened. The 15th is provided 

 with a very strong and long spine, whilst the others in the geno-type are 

 quite devoid of spines. Behind the 15th segment we find a number of 

 small thoracic segments of almost rudimentary character, and without spines. 



To judge from the remains that are known of these two forms it is 

 not probable that they have possessed a thoracic structure that entirely 

 agreed with Mesojiacis Vennontaiia. In any case it has not been possible 

 to determine with certainty any of the features mentioned above, and which 

 should be characteristic of this form. 



As far as Sclnjiicüicllits Torelli is especially concerned, I believe that 

 is it more probable that we are here confronted with a form that is 

 closel}' related to the Holniia genus, although it is not impossible that it 

 may belong to a différent genus. The hypostome exhibits a position be- 

 tween that of Holmia and Kjcrulfia, the pygidium and the pleurae of the 

 segments closely approach Uolniia, and the dorsal spines are built accor- 

 ding to the same type, although the posterior ones have been still more 

 strongl}- developed. 



The Estland form, too, Scliniidticllns Miclnvitzi may also conceivably 

 have stood near Holmia, or possibly the Kjcrulfia type. The structure of 

 the cranidium differs not inconsiderably from Torelli and reminds one 

 strongly of that which characterises the new family Kjcrulfia. 



It is to be hoped that new and more complete discoveries will give 

 us t'urther information on this question. 



As will be seen, of the previously known JMcsouacidae only the geno- 

 type Kjciulft Lnrs. can with certainty be allotted to the Holmia genus. 

 However, in all probability another Norwegian form, which 1 ha\e named 

 Holmia grandis nov. sp., also belongs to this genus. 



Holmia, Kjerulfi Linnarsson. 

 (PI. VI- VIII, XIV, fig. 31. 



1871. Paradoxides Kjerulfi I. G. O. Linnarsson, Om nagra fürsteningar fran Sveriges och 

 Norges „primordialzon" (Öfvers. af K. Vitensk. Akad. Förh. 187 1. Nr. 6, Pag. 790 — 

 792. pi. XVI, fig. 1—3). 



the first description, which however on account of imperfect material is far 

 from being exhaustive. 



