138 PALiEONTOLOGY OF NEW-YORK. 



fiin<>:u1a spatiosa ( n. b.)- 



Plate IX. Fio. 10 & 10 a. 



Shell broadly ovate, with beak acute, base broadly rounded, and sides 

 sloping in a gentle curve to the beak. Length a little greater than the 

 greatest breadth, which is at a point less than one-third the length 

 from the base. 



SuKFACE, which is partially exfoliated, marked by fine equidistant con- 

 centric lines, crossed by fine scarcely perceptible radiating lines (these 

 lines are much too strong in the figure). 



Fig. 10. The shell, natural size. 



Fig. 10 a. A portion of the surface enlarged. 



Geological position and locality. In the shaly limestone of the Lower Helderberg 

 group : Becraft's mountain near Hudson. 



In certain parts of the shaly limestone in the Lower Helderberg group 

 in Albany county, the lingulae are common fossils, occurring often in 

 fragments, and not unfrequently in the centre of phosphatic nodules 

 which have all the external aspect of coprolites. These masses sometimes 

 contain a single shell of Lingula in the centre, with few or no fragments 

 of similar shells in the surrounding mass ; while others are composed of 

 fragments of shells of lingulae with intermediate dark-colored impure 

 carbonate of lime, which effervesces very slowly in acid. These bodies 

 may probably be concretions where phosphatic material has aggregated 

 around the Lingula, or a similar mass when fragments of these shells 

 have formed the nucleus. The uniformly elongate oval or ovoid form, and 

 usually vertical position in the strata, are remarkable and interesting 

 features. A chemical analysis may perhaps furnish some information 

 suggestive of their origin. 



