650 CAMBRIAN BEACHIOPODA. 



Acrothele matthewi lata Matthew, Hall and Clarke, 1892, Nat. Hist. New York, Paleontology, vol. 8, pt. 1, PL III, 

 figs. 26-28. (No text reference. Figs. 27 and 28 are drawn from the specimen figured by Matthew, 1886, PI. V, 

 figs. 17 and 17a. Figs. 26 and 27 are copied from figs. 25 and 26, respectively, of the preceding reference.) 



Acrothele matthevn lata Matthew, 1895, Trans. New York Acad. Sci. for 1894-95, vol. 14, PL V, figs. 8a-b. (No text 

 reference. Figs. 8a-b are copied from Matthew, 1886, PL V, figs. 17 and 17a, respectively.) 



Acrothele matthewi lata Matthew, 1903, Geol. Survey Canada, Kept. Cambrian Rocks Cape Breton, p. 104, PL V, 

 figs. 6a-b. (Mentioned. Figs. 6a-b are copied from Matthew, 1902a, PL XVII, figs. 6a-b, respectively.) 



This variety is characterized by having a flatter rim that gives the valves a depressed 

 appearance around the border. There are many variations that tend to unite it with tj^ical 

 examples of the species, but there is no difiicultj^ in recognizing the typical forms of the variety. 



Formation and locality. — Middle Cambrian: (301 [Matthew, 1886, p. 42]) Sandstones of Division lb2 of Mat- 

 thew, on Hanford Brook; (301a [Matthew, 1895a, PL V, fig. 8]) fine-grained sandstones below the Protolenus-bearing shales 

 and sandstones in Division lb3 of Matthew, on Hanford Brook; and (301g [Matthew, 1886, p. 41]) sandstones of Division 

 Ic of Matthew, at Portland (now a part of the city of St. John); all in St. John County, New Brunswick. 



Acrothele matthewi multicostata Matthew. 



Plate LXI, figures 5, 5a-c. 



Acrothele matthewi multicostata Matthew, 1897, Trans. Roy. Soc. Canada for 1897, 2d ser., vol. 3, sec. 4, No. 7, p. 168. 

 (Characterized as a new variety.) 



This variety is distinguished from the typical forms of the species by the presence of 

 numerous narrow, more or less obscure, radiating ribs. There is a gradation in this respect 

 to tjrpical forms of A. matthewi, where an occasional trace of ribs occur. The more anterior 

 position of the apex of the ventral valve serves to distinguish tliis variety from A. prima costata, 

 which occurs at a slightly lower horizon at the same locaUty. 



This form owes its varietal name to the numerous radiating ribs upon its sheU surface. 



Formation and locality. — Middle Cambrian: (2s and 2t) « Shales and interbedded limestone in tlie upper part 

 of the Paradoxides zone. Eastings Cove [Matthew, 1898b, p. 38'], on Kennebecasis Bay, 0.5 mile {0.8 km.) northeast of 

 Torrybum, on ike Intercolonial Railway, northeast of St. John; and (2 1) limestone at the base of the Paradoxides zone 

 [Matthew, 1895a, p. 108], on Hanford Brook; both in St. John County, New Brunswick. 



, Acrothele? minuta Walcott. 



Plate LXIII, figure 3. 



Acrothele? minuta Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 303. (Described as below aa anew species.) 



SheU minute, 1.5 mm. in diameter, subcircular in outline, gently convex, with a slight 

 median depression from the umbo to the anterior margin; back of the umbo there is a sharp 

 median depression between minute ridges on each of which there are two points or nipples. 

 Surface marked by fine concentric striae. Substance of shell apparently phospliatic. 



Tills interesting little species is represented by a single specimen. The generic reference 

 is somewhat doubtful. 



Formation and locality. — Middle Cambrian: (C6) Thin slabby limestone in the upper shale member of tbe 

 Kiulung group [Blackwelder, 1907a, pp. 37 and 41 (2d list of fossils), and fig. 10 (bed 12), p. 38], 2.5 miles (4 km.) 

 southwest of Yenchuang, Sintai district, Shantung, China. 



Acrothele nitida (Ford). 



Plate LVIII, figures 4, 4a. 



Obolella nitida Ford, 1873, Am. Jour. Sci., 3d ser., vol. 5, p. 213. (Described as on p. 651 as a new species.) 

 Obolella nitida Ford, Walcott, 1886, Bull. U. S. Geol. Survey No. 30, pp. 118-119, PL XI, fig. 2. (Original descrip- 

 tion copied. The specimen represented by fig. 2 is redrawn in this monograph, PL LVIII, fig. 4.) 

 ■Obolella nitida Ford, Walcott, 1891, Tenth Ann. Rept. U. S. Geol. Survey, p. 612, PL LXXII, fig. 1. (New localities 



mentioned. Figure copied from preceding reference.) 

 Obolella nitida Ford, Hall and Clarke, 1892, Nat. Hist. New York, Paleontology, vol. 8, pt. 1, p. 70. (Mentioned.) 



o2t is the type locality, though the specimens in the United States National Museum collections to whieh that number is assigned were 

 collected later than Matthew's type specimens. 



