I916. No. 10. THE LOWER CAMBRIAN HOl.MIA FAUNA. 59 



1873. Paradoxides Kjeridfi Lnrs. p. p., Th. Kierllf, Sparagmittjeldet, Universitetsprogram. 



pag. 72 & fig. 2, 3 & 5 pag. 83. 



Description of the occurence at Tomten with 3 illustratioiis of the form. Figs 



I & 4, however, are of the new form Kjeridfia lata. 

 1875 Paradoxides Kjeridfi Lnrs. \V. C. Brocger, Fossiler fra Öxna & Kletten iGeol. Füren. 



Förh. Bd. II. Pag. 5721. 



Mentions discovery of this form at Kletten and states that it seems to approach 



distincth- the American Paradoxides fOlenellitsi Tliuiiisoiii Hall. 

 1879. Paradoxides Olenelhis Kjeridfi Lnrs. \V. C. Brogger, Urn Paradoxidesskifrene ved 



Krekling iXyt Mag. f. Naturv. Bd. 24, pag. 441. 



Describes this form more thoroughly- than Linnarsson, and mentions its rela- 

 tionship to Paradoxides lOlenellus) Kjeridfi. Brogger was thus first to demonstrate 



the systematic position of this form. 

 1888. Olenellus Kjeridfi Lnrs. G .Holm. Om Olenellus Kjerulfi iGeol. Foren, i Stockholm 



Förh. Bd. IX. pag. 493). 



The best description of this form and on the whole one of the most classic 



descriptions of a Mesonacid. 

 1910. Hohnia Kjtridfi Lnrs. Ch. D. Walcott. O/e-z/é-Z/MS and other genera of the Mesonacidae. 



(Smithsox Mtsc. Coll. Vol. 53, No. 6, 19 10, page a88i. Refers to Holms description 



and mentions the position of the form with respect to other American forms. 



I ha\e here chietly mentioned only those works that describe and 

 mention this important form from Tomten. For the synonymic in general 

 we refer to the works of Holm and Walcott. 



Hohnia Kjerulfi Lnrs.. which is the most important form in our 

 Lower Cambrian tauna, has been described in considerable detail by Lin- 

 XARSso.N, Brogger and Holm. The description of the last-mentioned in 

 particular is so thorough and is accompanied by such exellent illustrations 

 that it might seem superfluous to make a new one. My large material 

 from Tomten, however, has shown that Holm's description is not quite 

 exhaustive, and that in certain respects it requires rectifying. This is due 

 in part to the fact that like earlier writers Holm confused it with the form 

 which in the present work is described as Kjeridfia lata nov. gen. <S: sp. 

 It is also of special interest that it has been possible to discover a series 

 of stages of growth, — right from the Profaspis stage — which throw 

 light upon the changes that this form has undergone during its ontogenetic 

 evolution. As Holm's description is adequate in most respects I will here 

 give merelv a short general account, and subsequently discuss in greater 

 detail the structural features upon which my material has thrown new light. 



Description. Most specimens are more or less compressed flat in 

 the shale; the original arching is therefore not easily determined. Now 

 and then, however, we find specimens that are not compressed, or only 

 slightly so, and these evidently reproduce the original form exactly. A 

 specimen of this kind is shown, e. g. in PI. VII, figs 1—3, illustrating a 

 cranidium in which one eye is splendidly preserved. 



