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ILLINOIS STATE GEOLOGICAL SURVEY 



Genus Lonchodina Bassler, 1925 



Type species: Lonchodina typicalis Ulrich and 

 Bassler 



Lonchodina furnishi Rexroad, n.sp. 

 Plate 4, figures 11-13 



Arched and slightly bowed unit, limbs 

 thickest at apex and thinning distally. Pos- 

 terior limb the shorter, about three-eighths 

 the length of anterior limb, bowed slightly 

 inward, bearing three or four small, dis- 

 crete denticles strongly compressed later- 

 ally, larger denticles toward posterior tip 

 of limb. Anterior limb the longer, typically 

 inclined downward and only slightly out- 

 ward, bearing seven laterally compressed, 

 recurved, discrete denticles of subequal 

 size. Apical denticle nearly twice as large 

 as denticles of anterior limb, recurved, lat- 

 erally compressed with sharp edges fore and 

 aft, edges in midline of each limb, base of 

 apical denticle expanded into flaring lips 

 about the subapical pit, inner lip flaring in 

 and posteriorly, outer lip flaring out and 

 anteriorly, resulting in a pit which is nearly 

 oval in outline with longest axis oblique to 

 axis of posterior bar. Aborally, faint me- 

 dian groove extends from apical pit to ex- 

 tremities of limbs. 



The species is named in honor of W. M. 

 Furnish of the State University of Iowa. 



Material studied. — 13 specimens. 



Distribution. — Glen Dean Formation of 

 Illinois, Indiana, and Kentucky. 



Repository. — Illinois State Geological 

 Survey, 3P49 (holotype), 3P50, 3P51 (par- 

 atypes). 



Lonchodina paraclaviger Rexroad, n.sp. 

 Plate 4, figures 7-10 

 Anterior and posterior limbs thickened, 

 bar-like, each nearly straight but together 

 forming an arched and outwardly bowed 

 unit. Considering the slight curvature of 

 the denticles of some specimens, the shorter 

 limb is designated the posterior limb in the 

 orientation of this species. Posterior limb 

 averages one-half length of anterior limb, 

 is slightly bowed convexly inward, typically 

 bears four small laterally compressed, dis- 



crete denticles. Anterior limb inclines out- 

 ward up to 35° from line of posterior bar, 

 is very slightly bowed outward, and bears 

 six, seven, or eight denticles which are lat- 

 erally compressed, sharp-edged fore and aft, 

 and in some specimens fused about a third 

 of the distance up from the base. In a num- 

 ber of specimens the denticles toward the 

 distal end of the bar are increasingly large. 

 Apical denticle usually, although not al- 

 ways, the largest denticle, sharp-edged fore 

 and aft, inner face the more convex, nearly 

 straight, may incline slightly posteriorly 

 and inward. Aboral margin of each limb 

 rounded with a faint median groove extend- 

 ing the length of each limb from a sub- 

 triangular apical pit which has a straight 

 outer margin and a sharply flaring inner 



lip. 



The thickening of the limbs of this spe- 

 cies results in a form approaching the genus 

 Geniculatus Hass. However, the accretion 

 of lamellae in building a heavier limbed 

 form has not progressed to the point of 

 building the geniculate unit characteristic 

 of Geniculatus. 



Material studied. — 19 specimens. 



Distribution. — Glen Dean Formation of 

 Illinois, Indiana, and Kentucky. 



Repository. — Illinois State Geological 

 Survey, 3P52 (holotype), 3P53, 3P54, 3P55 

 (para types). 



Lonchodina cf. L. paraclarki Hass 



Plate 4, figures 4 and 5 



Lonchodina paraclarki Hass, 1953, U. S. Geol. Sur- 

 vey Prof. Paper 243-F, p. 83, pi. 16, figs. 15, 16. 



The specimens from the Glen Dean For- 

 mation are very similar to the holotype of 

 L. paraclarki Hass. The apical denticles of 

 some Glen Dean specimens are slightly 

 broader and shorter than those of the holo- 

 type, but this may well come within the 

 range of individual variation. One of the 

 Glen Dean specimens has a complete pos- 

 terior bar which bears six widely spaced 

 denticles. This is contrary to the descrip- 

 tion of L. paraclarki, but in my opinion, 

 based on examination of the type speci- 



