PLATE IV. 
Lyriopecten parallelodontus. 
Page 40. 
Fig. 1. The exterior of an imperfect right valve, as obtained from an impression of the exterior of the 
shell in the matrix. The sinus in the margin of the posterior ear is represented as too deep. 
Fig. 2. The interior mould of the preceding valve, showing- the ligamental grooves. The specimen also 
preserves traces of the pallial line and muscular impression. 
Schoharie grit. Albany Co., N. Y. 
Lyriopecten orbiculatus. 
Page 42. 
See Plate 82. 
Fig. 3. The interior of a small left valve imbedded in shale, showing a very perfect outline. 
Hamilton group. Geneseo, Livingston Co., N. Y. 
Fig. 4. The exterior of an exfoliated left valve. This specimen is the original of fig. 1, p. 202, Geolog. 
Rept. Fourth Dist. N. Y. 
Encrinal limestone of the Hamilton group. Shore of Lake Erie, N. Y. 
Fig. 5. A left valve preserving a portion of the cardinal area. The ligamental area in the specimen shows 
sevex-al longitudinal grooves much stronger than represented; the figure is also too narrow 
and the anterior ear too obtuse. 
Hamilton group. Baileytown, iY. Y. 
Fig. 6. A large left valve, showing the obliquity of the body consequent to age, and the comparatively 
short hinge-line, although the latter is represented as too short in the figure. 
Hamilton group. Moscow, N. Y. 
Fig. 7. A portion of the ligamental area of the right valve of specimen X 3, showing the longitudinal 
grooves, with a slight bending outward under the beak. 
Hamilton group. York Centre, Livingston Co., N. Y. 
Fig. S. A large left valve preserving some portions of the test, and otherwise quite imperfect from mace¬ 
ration and exfoliation. 
Hamilton group. Canandaigua lake, N. Y. 
Lyriopecten macrodontus. 
Page 46. 
See Plate 8. 
Fig. 9. A large imperfect mould of the interior, showing- the coarse grooves of the ligamental area. 
The muscular impression is preserved in the specimen, but is not represented in the figure. 
Hamilton group. Worcester, Otsego Co., N Y. 
Lyriopecten anomi^eformis. 
Page 63. 
See Plates 10 and 82. 
Fig. 10. An imperfect right valve, showing a portion of the hinge area and the deep byssal sinus. The 
rays, as represented, are too strong; they should be fine, undulating and unequal in size. 
Chemung group. Chemung river. Upper Narrows, N. Y. 
Lyriopecten tricostatus. 
Page 48. 
See Plates 7 and 10. 
Fig. 11. An imperfect left valve. By a fault in the lithography, the secondary and tertiary rays are 
represented too nearly alike, instead of alternating in size and strength. 
Hamilton group. Near Summit, Schohame Co., N. Y. 
