PLATE IV. 



Lyriopecten parallelodontus. 



Page 40. 

 Fig. I. The exterii mperfecl 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. 



2. The interior mould of the pr ding valve, showing' the ligamental grooves. The specimen also 



preserves traces of the pallia] line and muscular impression. 

 Schoharie grit. Albany Co., N. Y. 



Lyriopecten orbiculatus. 



Page 4-2. 

 See Plate 82. 

 Pig. 3. The interior of a small left valve imbedded in shale, showing a very perfect outline. 



Hamilton group. Geneseo, Livingston Co., N. Y. 

 Pig. 4. The exterior of an exfoliated left valve. This specimen is the original of fig, 1. p. 202, Geolog. 

 Etept. 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 shi m B 

 several longitudinal grooves much stronger than represented; the figure is also too narrow 

 and the anterior ear too obtuse. 



Hamilton group. Baileytown. X. Y. 

 Pig. 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. 

 Pig. 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., X. Y. 

 Pig. 8. A large left valve preserving some portions of the test, and otherwise quite imperfect from mace- 

 ration and exfoliation. 



Hamilton group. Cdnandaigua lake, X. Y. 



Lyriopecten macrodontus. 



Page 46. 

 See Plate 8. 



Fig. '.I. A huge imperfect mould of the interior, showing tin arse gi ves 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 53. 



See Plates 10 and 82. 



Pig. 10. An imperfect right valve, showing a portion of the hinge area and the deep byssal sinus. The 



raj s. as represented, are too strong ; they should be fine, undulating and unequal in si/e. 

 Chemung group. Chemung river, Upper Narrows, N. Y. 



Lyriopecten tricostatos. 



Page 4S. 



See Plates 7 and 10. 

 Pig. 11. An imperfect left valve. Bj a fault in the lithography, the secondary and tertiary rays are 



represented t learlj alike, instead of alternating in si/e and strength. 



Hamilton group. Near Summit. Schoharie Co., N. Y. 



