ACKOTEETIDiE. 649 



to comprise large shells of A. Tnatihewi. In the larger shells the granules become coarser toward 

 the outer margms and are more irregularly distributed over the surface. 



Of the varieties named by Matthew, "A. matthewi prima" appears to be of specific value 

 on account of the position of the apex of the ventral valve. "Acrothele matthewi costata" is a 

 variety of A. prima, and A. matthewi multicostata and A. matthewi lata appear to be the only 

 varieties remaining that are sufficiently persistent and definite to be recognized, and even 

 these merge by many gradations into the typical forms of the species. 



The specific name was given in honor of Dr. G. F. Matthew. 



FoEMATioN AND LOCALITY. — Upper Cambrian: (3) Shaly limestones 300 feet (91.4 m.) above the Paradoxides zone, 

 Manuals Brook, Conception Bay, Newfoundland. 



Middle Cambrian: (la, 6n, and 61) Shales near the top of No. 6; (1) shales of zone A of No. 7; and (2) shales of 

 zone B of No. 7; all in the Manuels Brook section [Walcott, 1891b, p. 261] on Manuels Brook, Conception Bay, New- 

 foundland. 



(6g) Limestone near the base of the Middle Cambrian, the lowest horizon carrjdng Paradoxides, northwest side of 

 Chappie Arm Harbor, about 1 mile (1.6 km.) from its head. Trinity Bay, Newfoundland. 



(2 1 and 2m) Limestones and shales at the base of the Paradoxides zone [Matthew, 1895a, p. 108] on Hanford Brook; 

 (301h [Matthew, 1886, p. 41]) shales of Division Ic of Matthew, on Hanford Brook; (301i) beds of Division Ibl of Matthew, 

 on Hanford Brook; (3011 [Matthew, 1886, p. 41]) shales of Division Id of Matthew, on Porters Brook, St. Martins; (301g 

 [Matthew, 1886, p.41])a sandstones of Division Ic of Matthew, at Portland (now part of the city of St. John); (2s) 

 limestone in upper part of Paradoxides zone, at Hastings Cove [see Matthew, 1898b, p. 38], on Kennebecasis Bay, 0.5 

 mile (0.8 km.) northeast of Torryburn, on the Intercolonial Railway, northeast of St. John; (3b) shale at the base of 

 the Paradoxides zone, at the head of Seeley Street, St. John; (301k [Walcott, 1884a, p.l6]) shales of the St. John forma- 

 tion at St. John; and (301j [Walcott, 1884a, p. 16]) shales of the St. John formation at Ratcliffs Millstream; all in 

 St. John Comity, New Brunswick. 



Acrothele matthewi eryx Walcott. 



Plate LXI, figure 2. 



Acrothele matthewi eryx Walcott, 1905, Proc. U. S. Nat. Mus., vol. 29, p. 11. (Described and discussed as below as a 

 new variety.) 



In form, convexity, and size the ventral valve of the only specimen representing this 

 variety is very similar to the typical forms of Acrothele matthewi (Hartt). The shell is partly 

 exfoliated and shows a small oval pit about the pedicle opening and two narrow vascular 

 sinuses that extend from a point nearly back of the pit about the pedicle opening, forward, and 

 a little outward, about one-third the length of the valve. 



The shell is built up of several layers or lamellae that are smooth and shiny on the interior, 

 except where slightly roughened by faint vascular markings and obscure radiating striae; the 

 outer surface is dull and marked by concentric striae and lines of growth, and numerous fine, 

 irregular, often anastomosing, elevated lines that give the surface a rough appearance. 



The ventral valve is nearly circular, with a diameter of 6 mm. If this shell were associated 

 with Acrothele matthewi in the Middle Cambrian rocks of New Brunswick, I should not hestitate 

 to identify it with that species. In the absence of a series of specimens, and of representatives 

 of the dorsal valve, it is not certain that it is identical with Acrothele matthewi. 



Formation and locality. — Hlddle Cambrian: (C4) Limestone nodules at the base of the lower shale member of 

 the Kiulung group [Blackwelder, 1907a, pp. 37 and 40 (2d list of fossils), and fig. 10 (bed 4), p. 38], 3 miles (4.8 km.) 

 southwest of Yenchuang, Sintai district, Shantung, China. 



Acrothele matthewi lata Matthew. 



Plate LXI, figure 3. 



Acrothele matthewi lata Matthew, 1886, Trans. Roy. Soc. Canada for 1885, 1st ser., vol. 3, sec. 4, No. 4, p. 41, PI. V, 

 figs. 17 and 17a. (Described as a new variety. The specimen represented by figs. 17 and 17a is redrawn in this 

 monograph, PI. LXI, fig. 3.) 



Acrothele matthewi lata Matthew, Hall and Clarke, 1892, Eleventh Ann. Rept. State Geologist New York for 1891, 

 PI. Ill, figs. 25 and 26. (Fig. 26 is drawn from the specimen figured by Matthew, 1886, PI. V, figs. 17 and 17a.) 



a This species also occurs in Locality 308h, 



