OBOLID^. 487 



Lingulella concinna Matthew, 1903, Geol. Survey Canada, Kept. Cambrian Rocks Cape Breton, pp. 203-204, PI. XIV, 

 figs. 5a-b. (Description and figures copied from Matthew, 1901a, p. 273, PI. V, figs. 2a-b.) 



General form ovate. Ventral valve obtusely acuminate; dorsal valve broad, rounded 

 ovate; valves moderately convex. Surface of shell marked with numerous concentric Unes of 

 growth and with intervening bands of strise that are somewhat undulating. "V\Tien the outer 

 surface of the shell is exfoliated the shiny inner layers of the shell are marked by both con- 

 centric and radiating stnse. 



The shell is thin and formed of a thin outer layer, and several thin inner layers or lamellje. 

 In some of the layers of argillaceous shale the shell has a bluish tinge ^vith a ghstening surface, 

 often wrinlded and ridged by longitudinal compression and also compressed into transverse 

 ridges when the shell has been distorted by movement in the shale. In some of the 

 specimens in the sandy layers, a few concentric hnes of minute punctse occur on the posterior 

 portion of the inner surface. A large ventral valve has a length of 15 mm. with a width of 

 10 mm., and a dorsal valve 11 mm. in length has a width of 8 mm. The average length of 

 several hundred specimens of the ventral valve is from 6 to 7 mm. 



The cast of the area of the pedicle valve shows it to be rather long and well extended out 

 on the cardinal slopes. A clearly defined pedicle furrow divides it midway, and a narrow 

 flexure line occurs about halfway between the pedicle furrow and the outer margin. The area 

 is marked by fine strise of growth parallel to the margin. The area of the brachial valve is 

 short and seldom well preserved. 



The cast of the interior of the valves, both in the argillaceous and sandy shale, shows almost 

 no traces of vascular markings or muscle scars. 



Observations. — When studying this species in 1901 I had a few specimens which at the 

 time I considered to be identical with Lingulella hella (Walcott). During the season of 1901 

 S. Ward Ijoper collected many hundred specimens on McNeil Brook, and other localities in 

 Cape Breton, that clearly showed that Matthew [1901a, p. 273] was correct in assigning it to a 

 distinct species. I was not sure that his Lingulella lens (Matthew) was distinct, as the material 

 from which he described and figured it was badly crushed and broken, the fragments of shell 

 being embedded together in the limestone. None of the typical specimens show the apex of 

 the ventral valve. The one used in illustration by Matthew [1901a, PI. V, fig. 3a] has all the 

 apex broken away, and the shell is somewhat compressed laterally. A photograph of this 

 specimen of Lingulella lens (Matthew) is reproduced in Plate XXXIII, figure 1 . 



Among the collections made by Loper, there are a large number of shells crushed and 

 crowded together very much as in the typical material of Lingulella lens used by Matthew. 

 There are, however, in the accompanying shales large numbers of individual specimens which 

 are beautifully preserved, which illustrate the outline and conyexity of the shell. The series 

 illustrates the gro\vth of the shell, also the various forms in which it occurs owing to the differ- 

 ence in sediment in which it has been embedded. The material collected by Loper came from 

 several horizons of the Upper Cambrian. Matthew [1901a, pp. 273-274] assigns "Lingulella 

 concinna" to the Dictyonema zone, and "Lingula lens" to the Paraholina zone. 



The shells in the arenaceous shales on McAdam shore are clearly Lingulella concinna, 

 but in the calcareous layers the shells are different and I retain the name lens for them. 



I received from Dr. G. Lindstrom a specimen from the black Dictyonema shales of Skane, 

 Sweden, labeled "Lingulella nathorsti Linnarsson." This is evidently an accident, as that 

 species occurs only in the Lower Cambrian and the specimen is a broader shell much like that 

 of L. concinna of Cape Breton. With our present information it is provisionally referred to 

 L. concinna. 



Formation and locality. — Upper Cambrian: (31i) Shale and shaly limestone on McNeil Brook, 1.5 miles (2.4 

 km.) east of Marion Bridge; (307 [Matthew, 190S, p. 204]) shales of Division CScof Matthew on McLeodBrooh (=Barachois 

 River); (lOo) shales on west side of Barachois River; (lOn) shale in ravine on east side of Barachois Glen, 3 miles (4.8 km.) 

 from Barachois; (XOe, lOf, lOg, and lOh) shale on small east branch of Barachois River, about 0.75 mile (1.2 km.) north 

 of the crossroad fromBoisdale to Upper Leitches Creek; (8d and 372) shale at Upper Leitches Creek; (10m and 372a) 

 shale 2 miles (3.2 km.) south of the Boisdale Road from Upper Leitches Creek; (lOd and lOi) shale in high bank on 

 west side of Barachois River, just north of the Boisdale Road; (13h) shale on east bank of Barachois River, 1.5 miles 



