BRACHIOPODA. 401 
Rafinesquina minnesotensis.] 
RaFinesquina minnEsoTENSIS N. H. Winchell. 
PLATE XXXI, FIGS. 25—29. 
1844. Strophomena deltoidea OWEN (not CONRAD). Geological Exploration of Iowa, Wisconsin 
and Illinois, pl. xvi, fig. 8; pl. xvn, fig. 6. 
1852. Leptceena deltoidea OWEN (not CONRAD). Geological Report of Wisconsin, Iowa and Min- 
nesota, p. 620, tab. 2B, fig. 10 (not the middle figure). 
1862. Strophomena incrassata HALL (not 1847). Geology of Wisconsin, vol. i, p. 42, fig. 16. 
1873. Leptena deltoidea N. H. WiNcHELL. First Annual Report of the Geological and Natural 
History Survey of Minnesota, p. 101; Ibidem, Fifth Report, p. 148; 
: Ibidem, Eighth Report, p. 62. 
1881. Strophomena minnesotensis N. H. WINCHELL. Ibidem, Ninth Report, p. 120. 
1883. Strophomena incrassata HALL (not 1847). Second Annual Report New York State Geologist, 
pl. XXXvIt, figs. 1-5. 
1892. Rafinesquina incrassata HALL. Paleontology of New York, vol. viii, p. 281, pl. vim, figs 1-5. 
Compare Leptena incrassata HALL. Paleontology of New York, vol. i, p. 19, pl. Iv bis, figs. 2a-2d, 
1847. 
Original: description: ‘Shell semioblong or semioval, with the cardinal angle 
about 90°, or less than 90°; diameter from six to nine lines transversely, and from 
four and a half to eight lines perpendicularly [Wisconsin specimens attain a greater 
size]; the receiving [ventral] valve convex, sometimes more suddenly deflected after 
passing the visceral area; entering [dorsal] valve gently concave, but reflexed more 
rapidly about the margin; the exterior of the convex [ventral] valve marked by fine, 
radiating striz, every third, fourth or fifth one being larger than the intervening ones; 
interior of the convex [ventral] valve, which is best known from its frequent casts, 
shows a large muscular impression much resembling that of S. alternata as figured 
by Meek in vol. i, Pal. Ohio, plate vir, fig. 3c, but somewhat bilobate in front and 
larger in proportion to the size of the valve; scars of adductor muscles closely 
approximate, small and in many casts of this valve undistinguishable; behind they 
are separated (on the casts) by a short mesial ridge, which between them becomes a 
narrow mesial furrow and then a deep furrow, terminating at the sinus between the 
outer larger scars; the outer larger scars [diductors] are radiately striated from the 
beak [at the base of the dental lamella small adjustors are occasionally indicated]; 
their margins are strongly marked (on the cast) along their posterior sides by dis- 
tinct grooves formed by the dental plates, which diverge at once from the foramen 
at an angle of 100-120°, running nearly straight to the outer margins of the muscular 
scar, when they curve slightly towards the front; the anterior and lateral margins 
of the general muscular impression are slightly marked on the casts; outside of the 
muscular scar is a shallow marginal impressed line which is most evident at the 
cardinal angles as it converges toward the beak; interior edge of the cardinal line 
is carinate from the teeth to the cardinal angles; the details of the markings in the 
apex of the beak are seen on the valve itself to consist of two short, distinct, 
diverging ridges extending not much beyond the hinge teeth [enclosing the adductor 
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