636 CAMBRIAN BEACHIOPODA. 



examples show a median and two lateral septa in front of the callus.'' (See interior of dorsal 

 valve as shown by PL LXII, fig. Ig.) In the United States National Museum collection, from 

 Matthew's horizon E3a, I find 13 interiors of the ventral valve with short "callus" and 10 

 typical exteriors, also 22 dorsal valves. There are also fair specimens from horizons 3d and 

 3e. The shells of horizon 3a have the oblate form of Acrothele avia found at horizons 3d and Be. 



Acroihele avia differs from Acrothele proles Matthew in having the apex of the ventral 

 valve a httle nearer the posterior margin, but not so near as that of Acrothele prima (Matthew). 



Formation and locamty. — Middle Cambrian: (13d'') Sandstones 10 feet (3 m.) below Di-vision E2a; (13d and 

 13d') sandstones opposite the thii-d waterfall in Dugald Brook, between Divisions E2a and E2b; (lOp) sandstone just 

 below the waterfall in Di\dsion E2b; (131 and 131') sandstones of Division E3a; (344 [Matthew, 1903, p. 81]) sandy 

 shales of Division ESb; (344a [Matthew, 1903, p. 26]) sandy shales of Division ESc; (344b [Matthew, 1903, p. 81]) 

 sandy shales of Division E3d; (13n')a sandstones of Division ESe; and (13n) sandstones of Division E3f; all in Mat- 

 thew's [1903, p. 21] Etcheminian, on Dugald Brook, Indian River, eastern Cape Breton, Nova Scotia. 



(13m) Sandstones of Division E3f of Matthew's [1903, p. 76] Etcheminian, on Gillis Brook, Indian River; and 

 (lOp") sandstone on the small brook on the hill between the bridge over Indian River and McPhees Brook; both in 

 eastern Cape Breton, Nova Scotia. 



Acrothele avia puteis Matthew. 



Acrothele avia-puteis Matthew, 1902, Bull. Nat. Hist. Soc. New Brunswick, vol. 4, pt. 5, No. 20, p. 398, PI. XVI, 



figs. 5a-b. (Characterized as a new variety.) 

 Acroihele avia-puteis Matthew, 1903, Geol. Survey Canada, Rept. Cambrian Rocks Cape Breton, p. 100, PI. IV, figs. 



5a-b. (Characterization and figures copied from preceding reference.) 



This seems to be a variety of Acrothele avia Matthew. It differs in the possession of a pair 

 of pits, one of which lies on each side of the space between the foramen and the visceral callus, 

 partly overlapping each. The visceral callus is quite short in this form and has but little promi- 

 nence. The ridges on the surface of the shell are more regularly concentric than in the type, 

 and more sharply cut; about ten are found in the space of 1 millimeter. The cardinal area is 

 curved forward toward the top, and finely striated. The foramen is about a fifth of the length 

 of the valve from the cardinal line, and the front of the callus about a third. Vascular trunks 

 and branches are visible on the surface of the ventral valve as in J., avia. The dorsal valve 

 does not sensibly differ from that of A. avia. 



The largest valve seen was 8 mm. long and about the same width. 



The typical specimens of the ventral valve of Acrothele avia puteis are slightly different from 

 those of Acrothele avia, but not sufficiently so to show clearly in an illustration. The pits 

 beside the median line, between the pedicle aperture and the visceral callosity, do not appear 

 in the specimens of the species, and indeed the condition of the material is such that probably 

 they could not be distinguished if originally present. The visceral callosity is shorter and 

 much like that of Acrothele matthewi (Hartt). 



Foemation and locality. — Middle Cambrian: (13m) Sandstones of Division E3f of Matthew's [1903, p. 76] 

 Etcheminian, on Gillis Brook; and (344c [Mattheio, 1903, p. 100]) sandy shales of Division ESd of Matthew's Etche- 

 minian, on Gregwa Brook; both in the Indian River valley, eastern Cape Breton, Nova Scotia. 



Acrothele bellapunctata Walcott. 



Plate LVII, figures 3, 3a-b. 



Acrothele bellapunctata Walcott, 1908, Smithsonian Misc. Coll., vol. 53, No. 3, pp. 82-83, PI. VIII, figs. 9 and 9'. 

 (Described and discussed as below as a new species. Figs. 9 and 9' are copied in this monograph, PL LVII, 

 figs. 3 and 3b, respectively.) 



General form a broad transverse oval with the posterior side slightly flattened and arched 

 upward for a short distance below the apex. Ventral valve convex near the umbo and nearly 

 flat over the anterior portion of the valve; apex near the posterior margin. Foraminal aper- 

 ture apparently at the apex above a short, not distinctly marked, false area. Ventral valve 

 nearly flat and with the posterior margin curved downward so as to fill the space caused by 



a 13n' is the type locality, though the specimens in the United States National Museum collections to which that number is assigned were 

 collected later than the type specimens. 



