742 CAMBRIAN BRACHIOPODA. 



low; hinge area perceptible, but very narrow, longitudinally striated, and having a minute tooth on each side of the 

 very narrow and small foraminal opening. 



Surface ornamented with about forty or fifty fine, faint, radiating strise; those of the middle fifth are close, con- 

 tinuous, and straight; a few on each side of these are divergent, while those near the back of the shell are fainter, 

 closer than the last, and moderately arched outward toward the lateral borders. The surface of the valves is also 

 marked by very fine but distinct concentric strise, and at somewhat regular intervals by about twelve more distinct 

 lines of growth. The concentric strise are usually as distinct as the radiating. Casts of the interior of the valves exhibit 

 a smooth surface with some irregular, sinous, radiating strise. 



Length, 7 mm.; width, 11 mm. Length of hinge line, 8 mm. 



Ohservations. — Doctor Matthew kindly sent me the typical specimens of this species, and 

 from them and specimens in the collections of the United States National Museum sufficient 

 data were obtained to clearly show that the species belongs to Protorihis and not Kutorgina. 

 In figure 3b, Plate XCIX, the free spondylium is present. As far as laiown, the characters 

 of the area, teeth, and free spondylium are the same as in P. billingsi. The smooth 

 casts suggest Kutorgina [Hall and Clarke, 1892c, PI. IV, figs. 18-20], but the ribbed shells 

 recall P. quacoensis, and the area with open delthyrium and free spondylium places the species 

 in ProtortMs. Its very fine surface ribs differentiate P. latourensis from all other described 

 species. 



The form described by Matthew [1886, p. 43, PI. V, fig. 19] as "Kutorgina pterineoides" is 

 not taken up in this monograph. The species is represented by one distorted specimen which 

 may not even be a brachiopod. 



Formation and locality. — Middle Cambrian: (301w) Shales of Division lc2 of Mattheiv's section; (308h) shales 

 of Division Icl of Matthew's section; and (301g) shales of Division Ic of Matthew; all at Portland (now part of the 

 city of St. John), St. John County, New Brunswick. 



Protorthis quacoensis (Matthew). 

 "^ Plate XCIX, figures 2, 2a-e. 



Orthis quacoensis Matthew, 1886, Trans. Roy. Soc. Canada, vol. 3, sec. 4, No. 4, pp. 43^4, PI. V, figs. 20, 20a-c. (De- 

 scribed and discussed. The two specimens represented by figs. 20-20a and 20b-20c are redrawn in this 

 monograph, PI. XCIX, figs. 2e and 2b, respectively.) 



Orthisina? quacoensis Matthew, 1891, Trans. Roy. Soc. Canada, 1st ser., vol. 8, sec. 4, No. 6, p. 131. (Mentioned and 

 generic reference changed.) 



Protorthis quacoensis (Matthew), Hall and Clarke, 1892, Nat. Hist. New York, Paleontology, vol. 8, pt. 1, p. 232, 

 PI. VIIA, fig. 21. (Changes generic reference.) 



Billingsella quacoensis (Matthew), Schuchert, 1897, Bull. U. S. Geol. Survey No. 87, p. 159. (Merely changes generic 

 reference.) 



Protorthis quacoensis (Matthew), Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, pp. 284-285. (Original description, 

 Matthew, 1886, pp. 43-44, copied and species discussed as below.) 



The original description by Matthew follows : 



A small species. Subquadrate to semielliptical in outline, broader than long, widest near or at the hinge line, 

 which is not produced; moderately convex, highest in the posterior third, flattened toward the front and sides. 

 Umbones not prominent. 



The dorsal valve rises rapidly from the hinge line, and has but a narrow, flattened space at the angles. It is about 

 one-third as high as it is long. The hinge plate has a narrow area, which is striated lengthwise, and bears two tooth- 

 like processes close to the umbo, the point of which is bent down to the hinge line. 



The ventral valve is somewhat more elevated than the dorsal. Hinge area triangular, sloping backward to the 

 umbo, and bearing fine stria parallel to the hinge line. Umbo elevated above the hinge line to a height fully equal to 

 one-third of the length of the valve. Foramen (delthyrium) large, truncate-pyramidal in outline. 



Surface of the valves ornamented by about twenty rounded plicse, radiating (in the ventral valve) from the edge 

 of the hinge area; opposite the foramen (delthyrium) and not from the beak alone; those on the middle fifth of each 

 valve are crowded together; those outside of these are more prominent, and are continuous from the umbo; those 

 toward the hinge line are faintly marked and widely separated. The radiating plicae do not (or rarely) increase by 

 bifurcation. Both valves bear numerous concentric strise and are also marked by a few distinct squamose lines of growth. 



The mold or cast of the interior of the valves of this species is nearly smooth, or is marked Ijy faint radiating 

 strise; the margm of the mold, however, often exhibits a crenulated appearance corresponding to the plicse of the 

 outer' surface. There is a wide, smooth median depression at the top of the mold of the dorsal valve, near the umbo. 



Length of the valve in 0. quacoensis, 5 mm.; width, 8 mm. 



