ACKOTRETID^. 663 



of the ventral valve is large and clearly defined, as in Botsfordia granvlata (Redlich), and the 

 main vascular sinuses are very strong and close to the pedicle aperture, as in the latter species. 

 In the interior of the dorsal valve the cardinal scars are very large and extend forward nearly 

 one-tliird the length of the valve. 



Type. — Acrothele granulata Linnarsson. 



I was at first inchned to place this form under Botsfordia, but the advanced position of the 

 apex and pedicle opening of the ventral valve indicates a closer affihation with Acrothele. The 

 short Ustrium of Botsfordia has developed in Redlichella to the strong false area of Acrothele, 

 but the visceral area and main vascular sinuses of Botsfordia remain practically unchanged. 

 I regard Redlichella as a form intermediate in development between Botsfordia and Acrothele. 



The subgeneric name is given for Dr. Karl A. Redlich, of the Geological Survey of India. 



Acrothele (Redlichella) granulata (Linnarsson). 

 ^ Plate LVI, figures 2, 2a-n. 



Acrothele granulata Linnarsson, 1876, Bihang till K. svensk. V-«t.-Akad. Handl., Bd. 3, No. 12, p. 24, PI. IV, figs. 



51a-c (and 52?). (Described and discussed in English as a new species.) 

 Acrothele sp., A. granulata Linnarsson, Swanston, 1877, Proc. Belfast Naturalists' Field Club, Appendix 4, for 1876-77, 



PI. VII, figs. 20a-c. (No text reference.) 

 Acrothele granulata Linnarsson, 1877, Geol. Foren. i Stockholm Forhandl., No. 40, Bd. 3, No. 12, pp. 373-374, PI. 



XV, figs. 12, 12a-b. (Described in Swedish.) 

 Acrothele granulata Linnarsson, Davidson, 1883, British Fossil Brachiopoda, vol. 5, pt. 2, p. 214, PL XVI, figs. 29, 



29a, 30, 30a-b. (Original description copied and species discussed.) 

 Acrothele granulata Linnarsson, Walcott, 1886, Bull. U. S. Geol. Survey No. 30, p. 109. (Mentioned as closely related 



to Acrothele subsidua.) 

 Acrothele sp., A. granulata Linnarsson, Swanston, 1886, Systematic Lists, Flora, Fauna, Paleontology, and Archae- 

 ology, North of Ireland, vol. 1, PI. VII, figs. 20a-c. (Reprint of Swanston, 1877, PI. VII, figs. 20a-c.) 

 Acrothele granulata Linnarsson, Hall and Clarke, 1892, Nat. Hist. New York, Paleontology, vol. 8, pt. 1, pp. 100- 



101. (Discussed.) 



The shell of Acrothele (Redlichella) granulata resembles so closely that of Acrothele coriacea 

 Linnarsson (p. 642) that I will only call attention to the points of difference between them. 



On the average, A. (R.) granulata is a longer, stronger shell; its surface is more coarsely 

 granular, the pedicle aperture is much larger, and the tubercles in front of it much smaller. 

 The false area is usually less distinct, but it is sometimes distinct and has a longitudinal median 

 line; the posterior margin arches up at the false area, and the dorsal valve arches up so as to 

 fit closely against the curved margin; the interior of the ventral valve of A. (R.) granulata 

 has a visceral area that is obtusely pointed in front and on each side extends out to the main 

 vascular sinuses, which originate nearer the pedicle opening than in A. coriacea. The main 

 vascular sinuses of A. (R.) granulata are much nearer the median line than those of A. coriacea. 

 The difference in the visceral area and vascular sinuses was found in specimens from the Para- 

 doxides forchhammeri beds of Gudhem, and also the P. cdandicus zone of Bornholm. 



In the dorsal valve of A. (R.) granulata the cardinal scars are longer and nearer the median 

 ridge. 



A large ventral valve has a length of 9 mm.; width, 10.5 mm. A large dorsal valve has 

 a length of 10 mm. ; width, 12 mm. 



Acrothele (Redlichella) granulata is a form intermediate between the typical Acrothele 

 coriacea Linnarsson and Botsfordia granulata (Redlich). It has the exterior appearance of 

 Acrothele coriacea, and the apex of the ventral valve is well in advance of the posterior margin, 

 but the interior of the ventral valve has the strongly marked visceral area of Botsfordia gran- 

 ulata, and strong vascular sinuses that are close to the pedicle opening. 



Formation and locality. — Middle Cambrian: (8z) Limestones of Paradoxides celandicus zone at Borgholm, 

 Oeland Island; (309f) shale at Borgholm, Oeland Island; (310o) limestone of the Paradoxides tessini zone at Borgholm, 

 Oeland Island; (320s [Linnarsson, 1877, p. 374]) at St. Fro, Oeland Island; (320b) limestones forming 2d of the Para- 

 doxides zone, the Agnostus Isevigatus horizon, at Gudhem, 12. .5 miles (20.1 km.) south-southeast of Skara, Province 

 of Skaraborg; {320 i [Linnarsson, 1876, p. 24\) drift blocks supposed to have come froin the Paradoxides celandicus zone 

 [Linnarsson, 1876, p. 6], at Lillviken, near Oestersund, Province of Jemtland; and (320t [Linnarsson, 1876, p. 24]) on 

 Billstaan River, parish of Hackas, Province of Jemtland; all in Sweden. 



