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high, being about one-fifth of the length of the valve ; the cardinal 

 slopes and pseudodeltidium are of about equal width, and the latter is 

 obliquely striated. The pedicle groove suddenly contracts in width 

 toward the beak. The visceral callus is narrow and extends forward 

 about half of the length of the valve ; on each side of it runs a vascular 

 line, marking the advance of the anterior adductors. On each side of 

 the valve, half way between the callus aud the margin, run the vascular 

 lines that mark the advance of the lateral muscles ; these extend nearly 

 as far forward as the callus. The margins of the valves are flattened on 

 the inside. 



The dorsal valve is more obtusely rounded behind than the ventral, 

 and in some examples is more tumid. Interior. The height of the 

 hinge area is about one-tenth of the length of the valve. The callus is 

 quite long, extending four-fifths of the length of the valve ; along the 

 middle of the valve it is divided by a distinct median septum ; the front 

 of the anterior adductor scars is about one third from the front of the 

 valve ; the lateral vascular ridges extend one-half of the length of the 

 valve, from the hinge. 



Sculpture. This consists of wavy, beaded ridges, that sometimes anas- 

 tomose ; there are about eight in the space of a millimetre. 



Size. Length of ventral valve 9 mm. ; width 6 mm ; depth about 

 mm. The dorsal valve is nearly 1 mm. shorter. 



Horizon and locality. In the shales of E. 1 c and e, Dugald brook, 

 Escasonie, N.S. 



As seen in Assise E. 1 e, this species is distinguished by its long oval 

 form and the projecting beak of the ventral valve. The callus of the 

 ventral valve is a straight narrow band, and the striae of the hinge- 

 area run a long way forward on the edges of the valves. 



This species in its oval form and elongated callus in both valves recalls 

 Leptobolus, but the strong development of the hinge, the rather thick 

 shell, and the coarse wavy ornamentation of the surface of its valves, 

 seem to exclude it from that genus, as also the approximation of th vas- 

 cular trunks in the ventral valve. Still it may be regarded as the repre- 

 sentative in this fauna of Leptobolus collicia of the Upper Etcheminian. 



It is not " satchel shaped ", that is squared at the front and angulate 

 behind, and so is not a typical Lingulella, but it is a common type of 

 Lingulelloid shell, for similar forms are to be met with throughout the 

 Cambrian system ; it is among the oldest Cambrian types, being found 

 in the Coldbrook volcanic terrane. 



