224 PALAEONTOLOGY OF KENTUCKY. 







thirteen or fourteen on the body of the shell, with intermediate smaller ones ; 

 about five obscure rays on the posterior wing ; the radiating costae crossed by 

 coarse, distant, lamellose, concentric ridges. 



Formation and Locality. Found in the hydraulic limestone of the Devonian formation at the 

 S*aih of the Ohio, in Kentucky and Indiana, where it is a rather rare shell. 



Aviculopecten fasciculatus. HALL. 



Plate III., figure 4. 

 Aviculopecten fasciculatus, Hall. Pal. N. Y., Vol. 5, pt. 1, page 11 1883. 



Shell small, obliquely and transversely ovate ; height about equal to length, 

 the former measuring more than seven-eighths of the latter. Pallial margins 

 regularly rounded, becoming more convex towards the middle of the posterio 

 lateral margin, and extending in a straight or slightly concave line to the 

 beaks. The left valve is only known to me ; it is slightly convex in its basal 

 half, but more so in the umbonal region ; the umbo is prominent, and the beak 

 pointed and incurved. The hinge-line is straight and shorter than the width 

 or length of the shell ; this is situated anterior to the middle of the cardinal 

 line. The anterior ear is considerably smaller than the posterior wing ; both 

 are triangular in shape, and both are defined by a sulcus, of which the posterior 

 one is more expressed and deeper. The posterior wing is very attenuate at the 

 extremity. Figure 4, plate 3, does not show the correct shape of the rear wing; 

 it should be more extended in the hinge-line, and should reach downward 

 only half as far as it does in that figure. The terminal margins of both wings 

 should be concave, and should join the lateral margins of the shell in a regular 

 curve, and not, as represented in the figure, by straight lines. 



The test of this shell is ornamented with numerous filiform, radiating striae, 

 which are often fasciculate, and by fine concentric lines of growth. In young 

 shells the radii are regular, with a slight fasciculate arrangement. The concen- 

 tric lines are sharper and more crowded on the wings, while the radii are very 

 much subdued, almost obscure. The interior of this shell is not known, 

 neither have I ever seen its right valve. 



The specimen here figured and described measures eight lines in height, 

 nine lines in length, and its hinge-line is five lines long. This species has some 

 resemblance with A. formio, princeps and pecteniformis, but differs from them 

 partly by its form, and partly by its surface-markings ; from A. princeps 

 mainly by the presence of radii on its wings. 



Formation and Locality, Found in the Corniferous limestone of the Devonian formation in 

 Kentucky and Indiana, at and around the Falls of the Ohio. 



