OBOLELLID^. 595 



Valley. I have found no traces of it in the Atlantic province Cambrian formations. Strati- 

 graphically, it is, I believe, the oldest representative of its genus in America. 



Formation and locality. — Lower Cambrian: (392c [Billings, 1872a, p. 218]) At the Straits of Belleisle, 

 Labrador. 



(56b) Limestone bowlder in conglomerate, on the south shore of Orleans Island, below Quebec; (2o) limestone 

 bowlders in conglomerate, on shore at east entrance to harbor at Bic, Rimouski County; and (319b) conglomeratic 

 limestones containing Olenellus ?, at St. Simon; all in Quebec, Canada. 



(319k) Calcareous sandstone near the base of the section west of Parker's quarry, on cliff overlooking Lake 

 Champlain, east of Georgia, Franklin County, Vermont. 



(2b) o Limestone just north of Beman Park, in the northeastern part of the city of Troy, Troy quadrangle (U. S. 

 Geol. Survey); (27) even-bedded and conglomerate limestones on the ridge in the eastern suburb of Troy, Troy 

 quadrangle (U. S. Geol. Survey); (338q [Hall, 1847, p. 290]) calcareous beds 3 miles (3.2 km.) northeast of Troy, Troy 

 quadrangle ( TJ. 8. Geol: Survey); (27a) reddish sandstone about 1 mile (1.6 km.) east of Lansingburg, north of Troy, 

 Cohoes quadrangle (U. S. Geol. Survey); and (29a) limestone 1 mile (1.6 km.) below the New York Central Railroad 

 depot at Schodack; all in Rensselaer County, New York. 



(338o) Shale on Moses Hill, 2 miles (3.2 km.) west of North Greenwich; and (35) limestones 1. Smiles (2.4 km.) 

 north of Bald Mountain; both in the Schuylerville quadrangle (U. S. Geol. Survey), Washington County,* New 

 York. 



(326d) "Station 2 " of Grabau [1900, p. 610] near North Attleboro, Bristol County; and (326g [Grabau, 1900, p. 

 620]) limestones at East Point, Nahant, Essex County; both in Massachusetts. 



Specimens that are somewhat doubtfully referred to this species occur at the following 

 localities : 



lower Cambrian: (50a) Sandstone 2 miles (3.2 km.) northwest of York, York County; and (12v) sandstone 

 above the quartzite 1 mile (1.6 km.) west of Fruitville on Little Conestoga Creek, Manheim township, Lancaster 

 County; both in Pennsylvania. 



(59m) Weisner quartzite in the Roan iron mine, Bartow County, Georgia. 



Obolella ceassa elongata n. var. 



Plate LV, figures 5, 5a. 



In the collections from St. Simon there is an oval or elongate ovate form to which it 

 appears to be desirable to give a varietal name. Its surface is marked by stronger concentric 

 lines of growth than usually occur on the less elongate shells of 0. crassa (Hall), and the valves 

 especially the dorsal, are much more elongate than those of 0. crassa. One ventral valve of 

 the latter species from Troy, New York, is nearly as elongate (PI. LIV, fig. 2a), but it is broader 

 on the posterior half of the shell than those from St. Simon referred to the variety elongata. 



Formation and LOCALITY. — Lower Cambrian: (319b) Conglomeratic limestones containing Olenellusf, St. 

 Simon, Province of Quebec, Canada. 



Obolella groomi Matley. 



^ Text figure 52. page 596. 



Obolella{?) groomi Matley, 1902, Quart. Jour. Geol. Soc. London, vol. 58, pt. 1, pp. 137 and 139, figs. 1-2, p. 137. 

 (Described and discussed as a new species, see below for copy. Fig. 1 is copied on p. 596 as fig. 52.) 



The original description by Matley follows : 



Shell oval, moderately convex, about as long as wide, widest toward the front, which is moderately to well rounded. 

 Lateral margins straight or slightly convex, converging posteriorly to form a rounded beak. Hinge-area absent, or 

 not well defined. Sides usually somewhat defiected. Surface covered by about thirty small but well-marked, con- 

 centric, rugose ridges. No radial striae. Casts of the interior show nothing but very faint traces of markings. 



About 4.5 mm. long by 5 mm. wide. Type in Professor Groom's collection. Other specimens measure: 



Length. Width. 



mm. mm. 



7 5.5 



5.5 5 



4.5 4.75 



a The species also occurs at Locality 2d. 6 This species also occurs at Locality 20. 



