CAMBRIAN BRACHIOPODA — WALCOTT 83 



shell ; concentric undulations and ridges of growth also occur in a 

 more or less irregular manner. The inner layers or lamellae are 

 marked by fine, concentric, and rather strong radiating lines. The 

 shell is built up of numerous thin layers or lamellae of a corneous 

 appearance. 



A slightly compressed ventral valve has a length of 5 mm., with a 

 width of 6.5 mm. A ventral valve 4 mm. in length has a width of 

 5 mm. 



This is one of the most beautifully ornamented species of the 

 genus. Its surface is not unlike that of some varieties of Micro- 

 mitra (Iphidella) pannula (White) [1874, p. 6]. In form it sug- 

 gests .4cro^/z(?/^ {Redlichclla) grannlata (Linnarsson) [1876, p. 24]- 

 Xothing is known of the interior character of the valves. 



Formation and Locality. — Lower Cambrian : Shales in upper 

 portion of Olcnellus kjerulfi zone, Ringsaker, Province of Hede- 

 marken, Norway. 



ACROTHELE BERGERONI, new species 



Plate 8, Figure ii 



La Disciiia MiquEl, 1893, No'te Snr la Geologic des Terrains Primaires 

 dti Departement de I'Herault, St. Chinian a Coulouma, p. 9. (Men- 

 tioned in French.) 



La Discina Miquel, 1894, Bull. Soc. d'fitude Sci. Nat. Beziers, for 1893, 

 Mem. Compte Rendu des Seances, XVI, 1894, p. 106. (This article is 

 a copy of the preceding reference, which was published as a separate.) 



La Discina MiquEl, 1894, Note Sur la Geologic des Terrains Primaires du 

 Departement de I'Herault, le Cambrien et I'Arenig, p. 10. (Mentioned 

 in French.) 



La Discina MiquEL, 1895, Bull. Soc. .d'fitude Sci. Nat. Beziers for 1894, 

 Mem. Compte Rendu des Seances, XVII, 1895, p. 10. (This article is 

 a copy of the preceding reference, which was published as a separate.) 



All the specimens representing this species are flattened by com- 

 pression in the argillaceous shale ; also more or less distorted. A 

 ventral valve 6 mm. in length has the apex 1.5 mm. from the pos- 

 terior margin. A cast of the interior of a ventral valve indicates a 

 relatively large interior opening for the pedicle tube ; a short, small 

 visceral cavity with the shell thickened so as to form a short ridge, 

 and an obscure false area; also that the posterior margin is arched 

 slightly above the plane of the margin of the valve. An exterior 

 cast shows the impression of a minute elongate tubercle on each 

 side of the apex and a small pedicle opening just back of them. A 

 cast of the interior of a dorsal valve shows a short median ridge and 

 the posterior portion of the main vascular sinuses. 

 3— w 



