OBOLID^. 409 



surface is marked by concentric lines of growth. The shell is built up of thin layers or 

 lamellae, those toward the front and sides being arranged obliquely to the surface, as in all of 

 the thick-shelled species of Oholus. 



Formation and locality. — XTpper Cambrian: (lOv) Shales in the "St. Croix sandstone," at Fox Glen, about 

 8 miles (12.8 km.) east of Baraboo, Baraboo quadrangle (IT. S. Geol. Survey), Sauk County, Wisconsin. 



Obolus prindlei (Walcott). 



Plate XXVII, figures 3, 3a-e. 



Oholus {Lingulella) prindlei Walcott, 1898, Proc. U. S. Nat. Mus., vol. 21, p. 412. (Characterized and discussed 

 essentially as below as a new species.) 



This species was at first considered to be identical with Lingulella granvillensis Walcott 

 (PI. XXII). The study of a new lot of well-preserved specimens shows that it differs from 

 granvillensis in being less elongate, more ovate in outline, and marked upon the interior by a 

 very finely granulated surface; in the cast the papillfe and the fine depressions between them 

 appear to be arranged in transverse undulating lines. The transverse lines of growth on 

 the area of the ventral valve, as seen in the cast, are peculiar in having an imbricating or 

 lamellose-like arrangement. The areas of both valves are rather large for so small a species. 

 The average length of the ventral valve is 3.5 mm. to 4 mm., and the width is 3.25 mm. The 

 dorsal valve is a little shorter than the ventral. 



Oholus prindlei belongs to a group of small shells (Pis. XXIX to XXXI) that is represented 

 by Lingulella ferruginea Salter, Oholus rotundatus (Walcott), Lingulella desiderata (Walcott), 

 Oholus chinensis (Walcott), Lingulella damesi (Walcott), and L. granvillensis Walcott. These 

 forms are among the earhest specimens of the genus and range through to the Ordovician fauna. 

 Lingulella granvillensis and Oholus prindlei occur in the upper limit of the Olenellus fauna of 

 eastern New York and western Vermont, and Oholus rotundatus and Lingulella manticula (White) 

 are found at the base of the Ordovician fauna. 



The specific name is given in recognition of the effective work of Mr. L. M. Prindle, who, as 

 assistant to Prof. T. Nelson Dale, collected the first specimens of the species. 



Formation and locality. — Lower Cambrian: (29) Limestone just above the bridge at the Stockport paper mill 

 on Kinderhook Creek, Columbia County; (35) limestones 1.5 miles (2.4 km.) north of Bald Mountain and 3.5 miles 

 (5.6 km.) north-northwest of Greenwich, Schuylerville quadrangle (U. S. Geol. Survey), Washington County; (45b) 

 limestone near the roadside about 1,200 feet (366 m.) east of Bristol's house, near Low Hampton, about 5 miles (8 km. ) east- 

 northeast of AATiitehall, Whitehall quadrangle (U. S. Geol. Survey), Washington County; (36b) limestones near school- 

 house No. 12, near Cireenwich, Cambridge quadrangle (U. S. Geol. Survey), Washington County; (38a) limestone 2 miles 

 (3.2 km.) south of North Granville, on the road which tm'ns south from the road running between that village and Truth- 

 villa, 4 miles (6.4 km.) west-northwest of Granville, Fort Ann quadrangle (U. S. Geol. Survey), Washington County; 

 (72) limestone 5 miles (8 km.) east of Albany, Kensselaer County; (2b) limestone just north of Beman Park, in the 

 northeastern part of the city of Troy, Rensselaer County; (338k) limestone 2.5 miles (4 km.) southwest of Wynants- 

 kill, Rensselaer County; and (72a) limestone 1 mile {1.6 km.) southioest of Wynantskill, Rensselaer County; all in New 

 York. 



Specimens that are compared with Oholus jjrindlei occur at the following locality: 



Lower Cambrian: (25a) Limestone on the Hall (Donaldson's) farm, 2 miles (3.2 km.) east of Swanton, Franklin 

 County, Vermont. 



Obolus refulgens Matthew. 



Plate IX, figures 2, 2a-d. 



Obolus refuljens Matthew, 1892, Trans. Roy. Soc. Canada, vol. 9, sec. 4, No. 5, pp. 44-45, PI. XII, figs. 6a-d. 



(Described and discussed as a new species. The specimens represented by figs. 6d (ventral) and 6d (dorsal) are 



redrawn in this monograph, PI. IX, figs. 2 and 2a, respectively.) 

 Obolus ? refulgens Mickwitz, 1896, M6m. Acad. imp. sci. St.-Petersbourg, 8th ser., vol. 4, No. 2, pp. 23-24. (Discussed 



in German.) 

 Obolus refulgens Matthew, 1902, Trans. Roy. Soc. Canada, 2d ser., vol. 8, sec. 4, No. 3, p. 96, plate opposite p. 112, 



figs, lla-b. (Discussed.) 

 Obolus (Monobolina) refulgens Matthew, 1902, idem, p. 98. (Changes generic reference.) 



