330 CAMBRIAN BRACHIOPODA. 



shown by Plate VI, figure Ik, except that the punctse are very few on the center of the shell, 

 which is the part enlarged by the figure. The inner layer of shell of M.formosa has numerous 

 large punctse that penetrate it, and also the irregular serpentine ridged shell deposits charac- 

 teristic of tliis species and of many adult shells of M. monilifera. 



Ohservations. — Wiman [1902, p. 53] created the genus Oausea to receive this species. He 

 very kindly sent me the type material for study, and with it a fine collection of M. monilifera 

 (Linnarsson) . I am unable to determine generic distinctions between the two species. The 

 shell substance and structure are the same, so far as material exists for comparison. Mickwitzia 

 formosa has a more elevated apex and is a much larger shell, but these are specific rather than 

 generic distinctions. 



Formation and locality. — Middle? Cambrian: (3111 [Wiman, 1902, p. 57]) Drift bowlder of bluish calcareous 

 sandstone, No. 31, on Biludden, about fO miles {32.2 km.) east ofGefle, Province ofGefleborg, Sweden. 



(311s [Wiman, 1902, p. 57]) Drift bowlder of gray quartzitic sandstone, at SkarpnS,t6, Aland Island, Finland, 

 Russia. 



Mickwitzia monilifera (Linnarsson). 

 Plate VI, figures 1, la-p; Plate LIX, figure 2. 



Lingulaf monilifera Linnarsson, 1869, Ofversigt af K. svensk. Vet.-Akad. Forhandl. for 1869, Bd. 26, No. 3, p. 344, 



PI. VII, figs. 1 and 2. (Described and discussed in Swedish as a new species.) 

 Lingula monilifera Linnarsson, 1869, Geol. Mag., vol. 6, p. 398, Pi. XI, figs. 1 and 2. (Text translated into English from 



Linnarsson, 1869a, p. 344. Figs. 1 and 2 are copied from Linnarsson, 1869a, PI. VII, figs. 1 and 2.) 

 Obolusf monilifer Linnarsson, 1871, Bihang till K. svensk. Vet.-Akad. Handl., Bd. 9, No. 7, pp. 9-10, PI. I, figs. 



2 and 3. (Described and discussed in Swedish.) 

 Mickwitzia monilifera (Linnarsson), Schmidt, 1888, Mem. Acad. imp. sci. St.-P6tersbourg, 7th ser., vol. 36, No. 2, 



pp. 21-23 and 24-25, PL II, figs. 6-26. (Described and discussed in German. Figs. 12c and 12d are copied 



in this monograph, PI. VI, figs. Ip and lo, respectively.) 

 Mickwitzia monilifera (Linnarsson), Walcott, 1891, Tenth Ann. Kept. U. S. Geol. Survey, PI. LXX, figs. 2, 2a-h. 



(No text reference. Figs. 2, 2a-f are copied from Schmidt, 1888, PI. II, figs.. 16a, 16c, 16b, 12b, 12c, 12d, and 



12a, respectively. Fig. 2h is copied from Linnarsson, 1871, PI. I, fig. 2.) 

 Mickwitzia monilifera (Linnarsson), Hall and Clarke, 1892, Eleventh Ann. Rept. State Geologist New York for 



1891, figs. 253-255, p. 246. (No text references. Figs. 25^-255 are copied from Schmidt, 1888, PI. II, figs. 14a, 



8b, and 16b, respectively.) 

 Mickwitzia monilifera (Linnarsson), Hall and Clarke, 1892, Forty-fifth Ann. Rept. New York State Museum for 1891, 



figs. 253-255, p. 562. (Copy of preceding reference.) 

 Mickwitzia monilifera (Linnarsson), Hall and Clarke, 1892, Nat. Hist. New York, Paleontology, vol. 8, pt. 1, p. 86, 



figs. 42-44. (No text reference. Figs. 42-44 are copied from Schmidt, 1888, PI. II, figs. 14a, 8b, and 16b, 



respectively.) 

 Mickwitzia monilifera (Linnarsson), Wiman, 1902, Bull. Geol. Inst. Univ. Upsala, vol. 6, pt. 1, No. 11, p. 53, PI. II, 



figs. 12-14, PL IV, figs. 2 and 3. (Characterized and discussed in German.) 



General form ovate to subcircular; biconvex or subplanoconvex. 



Surface of exterior of the shell papillose; each papilla is about as high as the width of 

 its base, and the apex is perforated by a minute tube. There appears to be no systematic 

 arrangement of the papillae; they are thickly set over the entire surface of a dorsal valve 20 mm. 

 in diameter; on some parts of the shell the papillae are closely arranged in undulating, irregular 

 ridges; these, when worn by attrition, have the appearance shown by Plate VI, figure Im. This 

 outer surface is rarely pi-eserved, as it usually adheres to the matrix, leaving the second layer 

 exposed to view. The layer of shell immediately beneath the outer shell is marked by concentric, 

 elevated, minutely undulating, raised, closely set lines that are crossed by fine, radiating, closely 

 set raised lines (PL VI, figs. Ik and 1 1) ; this is the surface illustrated by Linnarsson [1869b, 

 PI. XI, fig. 2] and Schmidt [1888, PL II, fig. 21]; it is seen on most specimens preserving the 

 shell. The distance from the apex, condition of preservation, etc., cause great variation in the 

 appearance of the inner layer. Scattered punctse penetrate the inner layer, and often the 

 depressions between the concentric and radiating raised lines give the surface a fiiiely and 

 regularly pitted or punctate appearance. On some shells the punctse are numerous and regu- 

 larly arranged toward the front of the shell. The inner surface of the inner layer of the shell 

 is marked by strong punctse in adult shells. Frequently a shell deposit is found over the inner 



