NO. 9 NEW YORK POTSDAM-HOYT FAUNA 263 



Genus TRIBLIDIUM Lindstrom 

 TRIBLIDIUM CORNUTAFORME Walcott 



Plate 41, figs. 12-14 



Metoptoma cornntaformc Walcott, 1879, Thirty-second Ann. Rept. New 

 York State Museum, p. 129. (Original description, as below.) 



Oval, subconical ; apex incurved, depressed, extending beyond the 

 anterior margin ; distance from the posterior margin to the apex 

 twice the width. The most elevated point is about two-thirds the 

 distance from the posterior margin to the apex ; from this point the 

 outline curves regularly to the posterior margin and anteriorly to the 

 apex. Outline from the apex to the anterior margin convex. Length, 

 18 mm. ; width, 9 mm. 



Surface, with narrow concentric ribs, i mm. apart ; finely striate 

 vertically. 



Formation and locality. — Upper Cambrian: (76) Arenaceous 

 Hoyt limestone at Hoyts quarry, 4 miles (6.4 km.) west of Saratoga 

 Springs, Saratoga County, New York. 



Genus MATHERELLA, new genus 



Univalve shells, sinistrally coiled ; spire composed of round volu- 

 tions that are more or less elevated ; umbilicus open ; peristome, so 

 far as known, entire, united with the preceding volution on the inner 

 side and probably not expanded to any considerable extent. 



Genotype. — Matherella saratogensis, new species. 



Stratigraphic range. — Upper Cambrian Hoyt limestone at Hoyts 

 quarry. 



Geographic distribution. — Saratoga County, New York, in the 

 United States. Doubtfully in Shantung, China. 



Observations. — This genus was recognized in 1886 and the name 

 Billingsia used for it in a list of fossils.^ As pointed out in the mono- 

 graph on the Cambrian Brachiopoda ^ this name was previously used 

 by both De Koninch (1876) and Ford (1886). 



Comparison may be made between Matherella and Scccvogyra 

 Whitfield.* Both shells are sinistrally coiled, with rounded volutions, 

 but Sccn'ogyra has a more or less trumpet-shaped peristome, and it 

 has rounded rather than flattened volutions. 



' Bull. U. S. Geol. Survey, No. 30, 1886, pp. 5, 21, 60, and 62. Also Bull. U. S. 

 Geol. Survey, No. 81, 1891, p. 346. 

 ^Monogr. U. S. Geol. Survey, Vol. 51, 1912, p. 561. (In press.) 

 " Geol. Surv. Wisconsin, Vol. 55, 1878, p. 198, pi. 3, figs. 7-9. 



