344 Prof. T. R. Jones on 
For these it will be convenient to adopt Leperditia fabulites 
as the specific name. 
Ill. Leperditia amygdalina, Ann. & Mag. Nat. Hist. 0. ¢. 
p- 841; decade ii. p. 97, figs. 18, 19. 
Of these L. fabulites, var. josephiana, is the largest, L. amyg- 
dalina is the next ; and the others (varieties of L. fabulites) 
diminish in size in the order given above. JL. amygdalina, 
from the Chazy Limestone, and L. canadensis (nana), from 
the Chazy Limestone and Calciferous Sandrock, are the oldest ; 
louckiana, from the Bird’s-eye Limestone, josephiana and 
pauquettiana, from the Trenton Limestone, and antzcostiana, 
from the Hudson-River group, succeed in geological age. The 
closely allied LZ. ovata of Pennsylvania* is also from a Lower 
Silurian rock, namely the Black-River Limestone, next above’ 
the Bird’s-eye Limestone. The more cylindrical form, L. 
Billingsit, sp. n., from near Lake Winnipeg, is, like some of 
the foregoing, from the Trenton Limestone. 
Pl. XIX. figs. 7, 8, and 9 illustrate some Canadian specimens 
described in 1858 (Ann. & Mag. Nat. Hist. ser. 3, vol. 1. 
pp. 840-342), but not figured at that time. 
Fig. 9, a perfect carapace of L. amygdalina, from L’Orignal, 
Canada West, has a length of 14 inch. This species varies 
somewhat in relative proportions among individuals, but keeps 
an elongate oblique ovate form and the forward position of 
its convexity. 
Fig. 8, a perfect carapace of ZL. fabulites (Conrad), var. 
anticostiana, +3 inch long, is rather shorter and higher, 
in proportion, than the smaller valve figured in the Canad. 
Surv. decade ii. Besides Hast Point other localities in 
Anticosti yield this Leperditia. In the ‘Catalogue of 
Anticosti Fossils,’ by W. Billings, 1866, at page 68 it is said 
to occur at the Jumpers and other places in “ Divisions 3 and 
4 of the Anticosti group.” 
Fig. 7, a perfect carapace of LZ. fabulites (Conrad), var. 
josephiana, 4 inch long, from St. Joseph’s Island, Lake Huron. 
The ventral margin sloping away from the front end, the well- 
rounded posterior margin, and the rather long hinge-line are 
features which bring this form near to the Scandinavian L. 
phaseolus ; but the latter is subcylindrical, having rather 
less ventral depth and a convexity along the middle of the 
valves. 
Pl. XX. fig. 7 is a right valve, in outline, of L. fabulites, 
var. josephiana, +5 inch long. The specimen came from St. 
Joseph’s Island, at the outlet of Lake Superior, and was 
given to me by Prof. James Hall in 1872. 
* Ann, & Mag. Nat. Hist. ser. 8, vol. i. p. 252, pl. x. fig, 14. 
