Bkede.] Carboniferous Invertebrate*. 99 



Our two species, Reticularia perplem and Spirifer earner atus, 

 belong to the Fimbriati and Aperturati respectively. Spiriferina 



is, in some respects, more closely related to the Lamellosi. 



Spirifer cameratus. Plate XII, figs, 5-5e. 



Spirifer cameratus Morton, Amer. Jour. Sci., xxix, p. 150, pi. n, f. 3, 

 (1836): etc. 



spirifer meusebachanus Roemer, Kreidebildung Texas, p. 88, pi. xi, f. 7» 



(185-2). 



Spirifer triplicates Hall, Stanbury's Expl. Surv. Gt. Salt Lake, p. 410, 



pi. iv, f. 5, (1852). 

 Spirifer fasiger Owen (non Keyserling), Geol. Surv. Iowa, Wis., and 



Minn., pi. v, f. 4, (1852). 

 Spirift r in equico status f Owen, ibid., p. 586, pi. v, f. 6, (1852). 

 Spirift r striatus var. triplicates Marcou, Geol. N. Amer., p. 49, pi. vn, 



f. 3, (1858). 

 Spirifera camerata Newberry, Ives' Rep. Colo. Riv. West, p. 127, (1861); 



etc. 



Spirift ra camt rata var. J:a)ipas( nsis Swallow, Trans. St. L. Acad. Sci., 



ii, p. 409, (1867). 

 Spirifer (Trir/onotrrfa) camerata Meek, King's U. S. Expl. 40th Parallel, 



iv, p. 91, pi. ix, f. 2, (1877). 



Shell medium to large in size, greatest convexity back of the 

 middle, variable in outline from subsemicircular to trigonal; 

 anterior margin sharply rounded to truncate-sinuate ; lateral 

 margins slightly curved to nearly straight, pointing outward 

 and backward to the ears ; hinge line equaling the greatest 

 width of the shell, sometimes prolonged into attenuate ears; 

 cardinal area broad, extending to the extremity of the hinge 

 line ; foramen broadly triangular and nearly equilateral, partly 

 closed in the upper part by a pseudo-deltidium ; beak high, 

 prominent, somewhat recurved over the cardinal area, which is 

 sometimes slightly arched ; mesial sinus prominent, beginning 

 at the beak and broadening and deepening until the front mar- 

 gin is reached ; fold of the dorsal valve to correspond, and the 

 beak of the same moderately rounded beneath that of the other 

 valve. Interior of pedicle valve marked by a subelliptical 

 muscular impression in the vicinity of the beak, posterior end 

 of this impression extending to the hinge line or beyond, 

 bisected by an indistinct mesial ridge, radiating from which 

 are small indistinct ridges for the attachment of the muscles. 

 The cardinal area projects over a portion of the visceral cavity, 



