PLATE IV. 

 Lyriopecten parallelodontus. 



Page 40. 

 Fiij. 1. The extenor f>f an imperfect i-iK-ht valve, as ohtaineil fmm an impression of the exterior of the 



shell in the mati-ix. The sinus in the margin of the posterior ear is represented as too deep. 

 Fig-. 2. 'ITie interior mould of the preceding valve, .showing the ligamental grooves. The specimen also 

 preserves traces of the jiallial lim: and muscular impression. 

 Schoharie grit. Alhany Co., N. T. 



Lyriopecten orbiculatus. 



Page i-2. 

 See Plate 82. 

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



Hamilton gi-oup. ffeiwseo, 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. 7. 

 Fig. 5. A left valve preserving a portion of the cardinal area. The ligamental area in the specimen shows 

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

 and the anterior ear too obtuse. 



Hamilton gi-oup. Baileytoum, iV. T. 

 Fig. C. A large left valve, showing the obliquity of the body consequent to age, ami the comjiaratively 

 short hinge-line, although the latter is represented as too short in the figure. 

 Hamilton gi'ou]). Moscow, N. Y. 

 Fig. 7. A portion of the ligamental area of the right valve of specimen X 3. showing the longitudinal 

 gi'Ooves, with a slight bending ovitward under the beak. 



Hamilton group. York Centre, Livingatoii Co., N. Y. 

 Fig. S. A large left valve j)reserving sonie portions of the test, and otherwise quite imperfect from mace- 

 ration and exfoliation. 



Hamilton group. CanandaigtM lake, N. T. 



Lyriopecten macrodontus. 



Page 46. 

 See Plate 8. 

 Fig. 9. A large imperfect mould of the interior, showing the coai-se grooves of the ligamental ai'ea. 

 The muscular impression is preserv<!<l in the s|iecimen, but is not i-epi-esented in the figin-e. 

 Hamilton group. IVorcester, Otiego Co., N Y. 



Lyriopecten anomijEformis. 



Page 63. 

 See Plates 10 and 82. 

 Fig. 10. An impei-fect right valve, showing a portion of the hinge area and the deep byssal sinus. The 

 I'ays, as represented, are too strong ; they should be fine, undulating and vmequal in size. 

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



Lyriopecten tricostatds. 



Page 48. 

 See Plates 7 and 10. 



Fig. 11. .\n 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, Scholtarie Co., N. Y. 



