Paleozoic Bivalved Entomostraca. 343 
Tennessee, who wrote, in the winter of 1858, to Mr. Billings, 
then of the Canadian Geological Survey, at Montreal, as 
follows :—“ The village in which I reside rests upon ‘Trenton 
and Black-river rocks. Many of the layers abound in Leper- 
ditia fabulites (Conrad). Thousands of them can be seen in 
half-an-hour’s walk. They are certainly Conrad’s species, as 
Mr. Jones has suspected. Several years ago I compared 
specimens from Mineral Point, Wisconsin®. ‘The average 
size is about that of fig. 16, plate xi. of the Decade, or per- 
haps a little smaller; but they occur of all sizes, from a third 
larger down to that of the figure of L. amygdalina (fig. 19, a), 
and even smaller.” 
Mr. Billings observed, in his letter of December 20, 1858 
(containing the above quotation), that “ Mineral Point is at 
no very great distance from St. Joseph’s, and in the same run 
of rocks; so that we might expect to find the species there ; 
but Tennessee is far from these localities. The geological 
position, however, is the same.” 
In view of adopting Conrad’s prior name (“‘ fabulites”’) for 
the common North-American Leperditia of the Lower-Silurian 
(Trenton) Limestone, we have to point out (as intimated 
above) that Leperditia canadensis, Jones, very variable in its 
individuals, can be grouped into two series: one set (I.) have 
a more subquadrate outline than the other (II.), which have a 
rather long hinge and an obliquely ovate body. ‘There is 
- another Lower-Silurian form (II1.), typified by LZ. amygdalina, 
which has a short hinge-line and a very oblique ovate body. 
I. L. canadensis, var. nana, Ann. & Mag. Nat. Hist. 1858, 
vol. i. p. 244, pl. ix. figs. 11,12; Geol. Surv. Canada, 
decade iii. p. 92, pl. xi. figs. 6, 7, 9, 10 (this I take to 
be typical, though small); and var. labrosa, Ann. & 
Mag. Nat. Hist. 7. c. p. 245; decade ii. p. 93, fig. 8: 
both from the Chazy Limestone. 
For these I propose to keep the specific designation of L. 
canadensis. 
II. Varieties—josephiana, Ann. & Mag. Nat. Hist. 7. c. 
pp- 340, 341; decade iii. p. 94, fig. 16 (“ fabulites,” 
Conrad): anticostiana, Ann. & Mag. Nat. Hist. . ¢. 
pp- 340, 341; dec. iii. p. 95, fig. 17: louckiana, Ann. 
& Mag. Nat. Hist. /. c. p. 245, pl.ix. fig. 16; dee. 111. 
p- 98, fig. 11: pauquettiana, Ann. & Mag. Nat. Hist. 
i. c. p. 246, pl. ix. fig. 17; dee. ii. p. 94, fig. 12. 
* Mineral Point is mentioned in the ‘Geology of Wisconsin; Surveys 
of 1873-7,’ vol. ii. 1877, at p. 682 &c.; and Leperditia fabulites is re- 
ferred to as abundant among the “Trenton” fossils, at pp. 294, 298, 
300, 302, and 325. si 
