PLATE XX. 



LEIOPTERIA ( ONRADI. 

 Pag 

 See Plate 88. 

 Pig, I . A large lefl \ alve. 



Hamilton gi p. Canandaigua lake, .V. I". 



_. A -| mien nt' i liiiMi size showing strong coi ntric undulations. 



Hamilton group. Bellona, Yates Co., A. 1". 

 i i left valve. Another figure of thi specimen i fiven on plate n->. 



Leiopteria Bigsbyi. 



I'm;;.' i 



See Plate 88. 

 I i .'!. II. Two lefl valves showing Hi.- form of tin' shell and the fine concentric sb 



L3, I 1. Two righl \ alves. 

 Pig. 15. A large lefl vah e. 



Hamilton group. Scho?iar'u Co., N. Y. 



Leiopteria L.T'.N 18. 

 Page 158 

 See Plate 17. 

 Pig. .">. A lefl valve enlarged to two diameters. 



Hamilton group. Ontario Co., N. Y. 



LEK IPTERIA RAFINESQUII. 

 Page 161. 

 See Plates 15 and 88. 

 Fig, 6. A small left valve. 



Hamilton group. Skaneateles lake, N. F, 

 Pig. 7. A larger example showing regular concentric undulations of the surface. 

 Hamilton group. Bellona, Yates Co., N. Y. 



Leiopteria Mitchelli. 



Page 166. 

 See Plate * s . 

 Fig. 8. A. left valve of this species. 



Hamilton gi'oup. From a boulder in th town of Catlierine, Schuyler Co., A'. 1". 



Leiopteria Greeni. 



Page 160 

 See Plate 88. 



Fig 9. A large individual retaining both valves partly ope I, showing tin' left valve and the cardinal 



\ iru hi' the righl \ alve. 



Hamilton group. Bellona, Yates Co., A'. 1'. 

 Fig. 1l'. An imperfect lefl valve preserving .-i portion of tin' test and showing tin- regular concentric 

 lamella;. 



Hamilton group. Prom m of Catherine, ScJiuyler Co., A'. 1". 



Leiopteria Oweni. 



Page IT" 

 i in. Tin' specimen described, showing tin' right valve ami tin' umbo of the left. 

 Hamilton group. Canandaigua lake, .V. 1". 



Leiopteria I >ekai r. 



Page ii;i. 

 See Plates 19 ami 88. 

 16 is. Three lefl valves differing somewhat in form and obliquity. 



I laiiiiltuii gi-oup. Otsego Co., N. ) 



Actinopteria deci SS VIA. 



Page III 

 See Plates 17. is ami 84. 



Fig. 19. A righl valve. The sj imen shows the pallial liar ami muscular impi sion which features are 



nol represented in tin- figure. 



Hamilton group. Madisi i Co., A. 1'. 



