2/6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



Strafigraphic range. — Lower Cambrian (Georgian) terrane in a 

 zone about 75 feet thick that is 270 feet below the zone of Paradox- 

 ides liicksi [Walcott, 1891, pp. 260-261]. Callavia broggeri occurs 

 in numbers 2 and 4 of the section. 



Geographic distribution. — Atlantic Coast Province, Callavia brog- 

 geri occurs about the head of Conception Bay, Newfoundland, and 

 C. crosbyi and C. biirrl in eastern Massachusetts near Weymouth. 

 Callavia callavei Lapworth is from central Shropshire, England. 



Observations. — Moberg [1899, p. 318, footnote] called attention 

 to the variation of Holmia broggeri Walcott. H. caUazei Lapworth, 

 and H. limdgreni Moberg from Holmia kjernlfi, Linnarsson, and 

 raised the question as to whether they should not form a new genus 

 or subgenus. With the new material furnished by Callavia crosbyi, 

 a form closely related to C. broggeri Walcott, formerly referred to 

 Holmia, and by Holmia roivei Walcott, I decided to group Olenellus 

 {Holmia) broggeri Walcott [1891], Olenellus callavei Lapworth 

 [1891, pp. 530-536], and the two species described in this paper as 

 Callavia crosbyi and C. burri under a new genus. Later I found 

 (hidden away in a footnote') that Dr. G. F. Matthew had proposed 

 the name Callavia to include the same species on account of the char- 

 acter of the glabella. 



Callavia broggeri [pi. 2"/, fig. i] differs from Holmia kjeriM Lin- 

 narsson [pi. 27, fig. 7], the genotype of Holmia, in having the first 

 lobe of the glabella constricted in front instead of expanded; in the 

 presence of a strong occipital spine, and in having broad, sickle- 

 shaped extensions of the pleurae [fig. 6] instead of sharp, spine-like 

 terminations as in H. kjerulii [fig. 7]. 



The glabella appears to be of a more primitive type than that of 

 Holmia, in this respect resembling the glabella of Nevadia [pi. 23, 

 fig. 3], and that of the young of Elliptocephala [pi. 25, figs. 13 

 and 14]. 



Callavia has the intergenal spines in the adult close to the genal 

 spines, and forming a part of the posterior margin of the cephalon, 

 instead of a distinct spine crossing it half way between the glabella 

 and genal spine, as in Holmia. 



Comparing Callavia and Holmia as to the stages of development 

 shown by their various parts, we find that the glabella of Callavia 

 is more primitive, the intergenal spine and pleuras less primitive. 



The comparisons between Callavia and IVanneria are made under 

 observations on the former genus [p. 247]. 



Matthew, 1897, p. 397, footnote. 



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