SILUKIAlf OSTEACODA FROM NOETH AMEEICA, ETC. 553 



2. Primitia mundula, J., with a little tubercle on each side of the 

 sulcus. 



'6. Primitia mundula, var. — Longer and narrower than the type ; 

 in some cases the sulcus is mid-dorsal ; in others it is much nearer 

 one end. 



4. Lepe7'ditiaj sp. nov. ? — Small, subconvex, oblong, with equally- 

 rounded ends. Also another, similar, but not showing the overlap 

 so clearly ; small and black. 



5. Beyrichia, sp. nov. — I^arrow-lobed ; the two lobes in front are 

 nearly equal in length, parallel, slightly curved upwards and for- 

 wards, joined below, and passing into the base of the hinder lobe, 

 which is variably compound. Eather frequent. 



6. Poly cope, sp. — Sublenticular, with a short, straight hinge-line. 



§ 2. Trenton Limestone. — Dark-grey limestone, which contains 

 Lituites undatus. Ealls of Lorette, Province of Quebec. 

 1. Leperditia, sp. nov. ? — Like § II. § 1, 4. 



§ 3. Birdseye Formation. — Pree specimens from the Birdseye 

 Limestone. Associated with Tetradium fihratum, Orthoceras muUi- 

 cameratum, Bathyurus eoctans, &c. Lot 3, Concession 3, E/iver 

 Pront 1, Gloucester Township, Co. Carleton, Ontario, Canada. 



1. Leperditia, sp. nov. ? — Subglobose, being relatively high and 

 thick ; ends not quite equal, the posterior curve being fuller and 

 bolder ; greatest height and greatest thickness a little behind the 

 middle. The overlap seems to extend all round the free margin. 



§ 4. Chazy Formation. Chazy Limestone. 

 § I. Pointe-aux-Pins, Aylmer, Province of Quebec, Canada. 

 1. Isocliilina ottaiua, Jones. Variety. Abundant in a dark- 

 grey limestone. 



§ II. South of St. John's Market, Quebec City. — Dark fine-grained 

 limestone. 



1. Primitia, sp. — Suboblong, neatly curved on the free margin, 

 which bears a nearly uniform flattened rim ; sulcus represented by 

 a distinct relatively large round pit. This may be related to P. re- 

 nulina, J. & H. 



2. Primitia, sp. — Suboblong, ends rounded, but narrower (lower) 

 in front than behind ; sulcus mid-dorsal, distinct, but not deep. 



§ III. Chazy Limestone. Broad-street Asylum, Quebec City. 



1. Leperditia, sp. nov. ? Small, dark-coloured, with the greatest 

 ventral curve in the middle ; front end subangular. Abundant in 

 a black limestone, especially on the bed-planes. 



§ IV. Chazy Shales. Broad-street Asylum, Quebec City. — Dark- 

 coloured, micaceous, shaly mudstone, somewhat ferruginous. 



1. Primitia mundula (?), J. — Hather large, with a deep sulcus, 

 which has one of its edges strongly tuberculate. 



2. Leperditia ? — Yery neat cast of the interior of a left valve, but 

 the eye-spot, muscle-mark, and ventral flange are not shown. The 

 greatest ventral curve is in the postero -ventral region. 



3. Beyrichia, sp. nov. — Ovate-obloug, broad-lobed ; the two main 



