PLATE LXII. 



(Figures 1-5, 8-10, 14-1(1, 21-i:!, 37-4.1, ai, 53 by E. Emmoss ; 7, S, ll-i:j, 17--.;o, ■J4-' . 4i; ."il l>y (i. li. siMi'sox.) 



Genus SYNTROPHIA, gen. xov. 



Page -na. 



Syjjtrophia lateralis, Whitfield. 



1. The exterior of a pedicle-valve ; showing the long, straight hinge hkI broad median sinus. 

 . The exterior of a Ijrachial valve ; showing the broad, obscure nieuian fold. 

 , The exterior of a small pedicle-valve. 

 A portion of the interior of the pedicle-valve ; showing the cardinal area and spondylium. X ■?. 

 Cardinal view of conjoined valves which have been transversely sectioned in the lunbonal region ; 

 showing the spondylium in both valves. The shell has been cut just in front of the support- 

 ing septa, the bi-achial valve lieing aljove. X -• 

 Caniinal view of the specimen represented in tig. 1 ; sliowing the cardinal ai'ea. 

 8. Internal casts of two brachial valves with impressions of vascular sinuses. 



, A portion of the interior of the pedicle-valve ; showing the complete spondylium and the division 

 of its surface into median (adductor) and lateral (diductor) muscular areas. X 3. 

 Fig. 10. Oblic^ue view of the specimen represented in fig. 1 ; showing the ele\ation of the spondylium and 

 the length of its supporting median septum. 



Calciferous formation (F<irt Cas.sin beds). Kort Casshi, Vti-iimiit. 



Genus CAMARELLA, Billings. 



Page aiii. 



Camarella Volborthi, Billings. 



Figs. 11, 12. Dorsal views of two shells ; showing a slight ilitference in outline and very faint median njar- 

 ginal plication. 



Trenton limestone, ■lack.vmburyh, N. Y 

 Figs. 13, 14, 15, 16. Profile, dorsal, ventral and front views of a more strongly plicated shell. X 2. 

 Fig. 17. Cardinal view of conjoined valves which have been transversely sectioned in the umbonal region ; 



showing the spondylium of the pedicle- valve and its median supporting septum. X 4. 

 Fig. 18. 'J'he interior of the umbonal portion of the brachial valve; showing the small apical spondslium 

 and the median septum. X 4. 



Black River limestone. Patiqiirlte's liapi.ds, Ottawa Miivr. 



Camakella Panueui, Billings. 



Figs. 19, 20. Dosral and front \ lews of an average example. 



Figs. 21, 22, 23. Dorsal, front and profile %iews of an indiviilual with no trace of lateral or marginal plica- 

 tions. X 2. 



Black River limestone. Pauqaette's Hapids, Ottawa River. 



Genus SYNTROPHIA. gen. nov. 



Page IK 

 SyNTROPIIIA (?) CALCIFERA, BilliilgS. 

 Fig. 24. The exterior of the pedicle-valve; showing the elevated umbo, deep median .sinus and extended 

 hinge-line. X 2. 



Quebec group. Pointe Levis, Canada. 



