J 9 1 6. No. lO. THE LOWER CAMBRIAN HOLMIA FAUNA. 55 



Genotype: Paradoxides Kjerulfi Linnarsson, 187 i . 



As is well known, this species which is typical of the genus, was 

 first described by Linnarsson as a Paradoxides in 1871 ^. A few years 

 latter, in 1875, Brogger drew attention to the circumstance that it should 

 be regarded as related to the American Olenellus forms-. In his admirable 

 description (1887 1 Holm ^ states that of the American species Oloicllns 

 {^= Elliptocephala) asaplwides Emmons should be the one that was most 

 nearly related. Soon after M.atthew proposed a new genus Holiuia for 

 this characteristic Scandinavian form and wrote as follows'*: > The four- 

 spined hypostome of 0. Kjerulfi is dift'erent from any known hypostome of 



an Olenellus or a Paradoxides Such a hypostome and the absence 



of an enlarged third segment of the thorax, separated this species from all 

 the American OlcucUi . 



Later on the genus was extended by Walcott and Lapworth-^ to 

 embrace other Mesouacidae, eg. Olenellus Broggcri Walcott and Olenellus 

 Callavei Lapworth. Lapworth proposed the formation of a sub-genus 

 Ccphalacanihiis. However, as shown by Walcott, ^LATTHE^v's name Holniia 

 had the priority, and the said forms were therefore placed by the two 

 scientists amongst the Holmia genus. Several scientists subsequently 

 concurred with this view, including Peach and Moberg^. In 1897, however 

 Matthew's demonstrated that two distinct types were united in the above 

 genus, and he proposed the new genus Callavia for O. Broggeri Walcott 

 and O. Collai'ci Lapworth, a proposal that has subsequently met with 

 unanimous approval. It ma}- also be mentioned that Frech ^^ in 1897 

 considered Holmia as identical with Borneman's genus Olenopsis, which 

 however, was distinctly refused by Pompeckj^^ and probably with justi- 

 fication. 



In his last work Walcott completely agrees with Matthew with 

 regard to the limitations of the Holniia genus, which he characterises as 

 having intergenal spines in adult specimens, a uniform series of thoracic 



1 „Om nàgra försteningar frân Sveriges och Norges Primordialzone" (Öfvers. K.V'et.Akad. 



Förh. 187 1, pag. 7891. 

 - Fossiler fra Oxna og Kletten (Geolog. FOrh. Bd. II. 1875, pag. 572.1 & Om Paradoxides- 



skifrene ved Krekling (N\-t Mag. for Naturv. 1879, ß^- 24, pag. 44I. 

 •' Om Olenellus Kjerulfi (Geol. Forh. Bd. IX, 1887, pag. 514 1. 

 ' Trans. Roy. Soc. Canada, Vol. VII, Sect. IV. 1890, pag. 160. 

 ^ Tenth Ann. Rept. U. S. Geol. Surv. 1891. page 641. 

 '^ Geol. Mag. Dec. 3, Vol. 8, page 531. 



" Quart. Joiirn. Geol. Soc. Vol. 48, (18921 page 236 and Vol. 50 (18941 page 671. 

 ^ Sveriges Äidste Kända Trilobiter (Geol. FOren. Stockholm FOrh. Vol. 21 (1899) page 318). 

 ■' American Geologist, Vol. 24, 1899, page 59. 

 ^^ Lethaea palaeozoica, Bd. II, 1897, pag. 41. 

 1^ Zeiischr-deiitsch Geol. Ges. Vol.53, içoi- pag- 14 — '7- 



