CAMBRIAN BRACHIOPODA WAI.COTT III 



Thin sections of the shell of the type species show it to be fibrous 

 and with many minute pores arranged in lines radiating from the 

 beak to the front and side margins of the valves. 



Type. — Polytoechia ? vwtitanensis Walcott [1905a, p. 295]. 



This genus is known only by the type species from the Lower 

 Ordovician of Montana. It is distinguished from Polytoechia Hall 

 and Clarke [1892&, p. 239] by an open delthyrium, smooth surface, 

 and presence of septa and spondylium in the dorsal valve. It dif- 

 fers from Syntrophia and Huenella in having several septa support- 

 ing the spondylia, and also from Huenella in having a smooth non- 

 plicate surface. 



The generic name is given in recognition of the work of Prof. 

 John M. Clarke, of the Geological Survey of New York, in connec- 

 tion with Prof. James Hall, on the fossil Brachiopoda. 



BIBLIOGRAPHY 

 Barrande, J. 



1879. Systeme Silurien du Centre de la Boheme, V, Pt. i, 1879, pp. 1-226, 

 plates 1-153; 4to, Prague. (Referred to on pp. 61, 84.) 

 BeechER, C. E. 



1891. American Journal of Science, 3d series, XLI, 1891 (April), pp. 

 343-357: Development of the Brachiopoda. (Referred to on 

 p. 58.) 

 Billings, E. 



18610. The Canadian Naturalist and Geologist, ist series, VI, No. 4, 1861 

 (August), pp. 310-328: On some of the rocks and fossils occur- 

 ring near Phillipsburg, Canada East. (Referred to on p. 107.) 

 1861&. Geological Survey of Canada, Paleozoic Fossils, I, 1861 (Novem- 

 ber), pp. 1-24. (Referred to on pp. 57, 59, 97, 98.) 

 1862. Geological Survey of Canada, Paleozoic Fossils, I, 1862 (June), 

 pp. 57-168. (Referred to on pp. 66, 85.) 

 Conrad, T. A. 



1839. Third Annual Report New York State Survey (printed as New 

 York State Assembly Document No. 275), 1839 (February 

 ^7)^ PP- 57-66: Second Annual Report of T. A. Conrad. (Re- 

 ferred to on p. 72.) 

 DwiGHT, W. B. 



1889. American Journal of Science, 3d series, XXXVIII, 1889 (August), 

 pp. 139-153 : Recent explorations in the Wappinger Valley lime- 

 stones and other formations of Dutchess Co., N. Y. (Referred 

 to on pp. 59, 102.) 



ElCHWALD, C. E. VON, 



1829. Zoologia specialis, quam expositis animalibus tum vivis, turn fossil- 

 ibus potissimum Rossise in universum, et Poloniae in specie, etc., 

 T, 1829; 8vo, Vilnae. (Referred to on pp. 61, 72-) 



