f PLATE X. 



Figure 1. Isochilina grandis, Jones, \B.r. latimarginata, now a, right valve ; b. 



ventral view ; c, end view. Nat. size. 

 ** 2. The same, a, right valve; b, ventral view; c, end view. Nat. size . 

 " 3. The same. Muscle-spot. Magn. twice. 



" 4. The same. Muscle-spot of another individual. Magn. three times, 

 " 5. Leperditia Hisingeri, Schmidt, var. fabulina, nov. a, left valve ; b. 



ventral edge; c, end view. Magn. twice. 

 " 6 Leperditia marginata, Schmidt, a, right valve ; b, ventral edge ; c, 



end view. Magn. twice. 

 *' 7 Leperditia Hisingeri, Schmidt, var. fabulina, nov. Two valves of a 



small individual, more or less imbedded. Magn. twice, 



Figs. 1-7 from Long Point, Lake Winnepegosis. 

 " 8 Primitia mundula, Jones, var. effossa, nov. Right valve. Magn. 15 



diam. Quebec City. 

 " 9 Primitia mundula, Jones, var. incisa, nov. a, right valve ; b, ventral 



edge ; c, end view. Magn. 15 diam. Lorette Falls. 

 ^.o— " 10 Isochilina Ottawa, Jones, var. intermedia, nov. a, left valve ; b, 

 ^y^ ventral view. Magn. 5 diam. Aylmer, Prov. Quebec. 



" 11 The same, var. intermedia, a, right valve ; Magn. 5 diam.; b, portion 

 y"^ of marginal rim ; Magn. 25 diam. 



" 12 Aparchites mundulus, sp. nov. Right valve. Magn. 15 diam. [The 



dorsal line is made too long in the figure.] Lorette Falls. 

 " 13. Isochilina Whiteavesii, sp. nov- a, left valve [the ventral margin is 



brought down too low in the figure] ; b, ventral edge. 



Magn. 10 diam. Lorette Falls. 

 " 14. Isochilina Amii, sp. nov. a, left valve ; b, ventral view. Magn. 10 



diam. Lorette Falls. 

 '* 15. Leperditia f ohscura, sp. nov. a, carapace left valve shown ; b, ven- 

 tral view of carapace, (the right valve represented only 



by its internal cast). Magn. 7 diam. Lorette Falls. 

 Isochilina labellosa, sp. nov. a, right valve ; b, ventral view. Magn. 



15 diam. Aylmer, Prov. Quebec. 

 The same. Left valve. Magn. 7 diam., Aylmer, Prov. Quebec. 

 Leperditia balthica (Hisinger), var primxva, nov. Right valve. 



Magn. 7 diam. Carleton Co., Ontario. 



/" 19. Isochilina labellosa, sp. nov. Ventral view. Magn. 7 diam. Aylmer, 

 Prov. Quebec. 



