NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT WJ 



(fig. 28). If each of the two curves were projected toward a point on 

 the length-axis somewhere less than 0.5 mm., each must necessarily 

 bend somewhat more strongly than shown by the points on the dia- 

 grams, indicating more pronounced allometry at the earlier stages in 

 shell growth. However, the stronger curvature of the hypothetically 

 projected trend in thickness indicates that the length and width of early 

 postlarval shells increased nearly commensurately, while the shells 

 remained very flat and thin until reaching a length of about 3-4 mm. 



Comparisons. — Coledium explanatum is characterized by its globose 

 shape, transverse adult outline, sharp pedicle beak without apical per- 



Table 22. — Measurements of Coledium explanatum from the lower part of Fay- 

 etteville Shale, 2 miles north of Habberton, Ark. 



Measurements, in millimeters 



Table 23. — Measurements of Coledium explanatum from the upper part of Ches- 

 ter Series, 2 miles south of Marion, Ky. 



Measurements, in millimeters 



Fig. 28. — Scatter diagrams of dimensions of Coledium explanatum. Circles 

 represent specimens from 2 miles south of Marion, Ky. ; solid dots represents 

 specimens from 2 miles north of Baldwin, 111. ; triangles represent specimens from 

 2 miles north of Habberton, Ark. 



