340 Prof. T. R. Jones on the 



Nat. Ilist. 1881, ser. 5, vol. viii. p. S^U ; Fr. Schmidt, Mt5m. Acad. 

 Iinper. Sci. St.-Petersb. 187.3, ser. 7, vol. xxi. no. 2, and 1883, 

 vol. xxxi. no. 5. Also other authors. 



1. Leperditia canadensis ^ Jones. 



Leper difia canadensis, Jones, Ann. & Mag. Nat. Hist. 1858, ser. .3, vol. i. 

 p. 244, pi. ix. figs. 11-15 (including var. nana and var. labrosa) ; 

 Geol. Surv. Canada, dec. iii. 1858, pi. xi. fips. (i-10 ; Ann. >S: Mag. 

 Nat. Hist. 1881, ser. 5, vol. viii. p. 343, and p. 345, pi. xx. tig. 5. 



Specimen in the McGill University Museum. Labelled 

 " Lake JVlatapedia." Gvey, crystalline, encrinital limestone. 

 Two individuals, one of them good ; i inch long, i high. 



Leperditia canadensis^ Jones, as restricted in the Ann. & 

 Mag. Nat. Hist. November 1883, p. 343. 



L. canadensis was originally found in the " Calcifevous 

 Sandrock " of Grenville*. 



2. Leperditia louckiana, Jones. 



Leperditia canadensis ?, Jones, Ann. & ^lag. Nat. Hist. 1858, ser. 3, 



vol. i. p. 24-5, pi. ix. figs. K!, 17 [afterwards var. louckiana and var. 



jjauqtwttianaX 

 Leperditia canadensis, var. louckiana, Jones, Geol. Surv. Canada, 1858, 



dec. iii. pi. xi. fig. 11. 

 Leperditia fabulites (Conrad), var. louckiana, Jones, Ann. & Mag. Nat. 



Hist. 1881, ser. 5, vol. viii. p. 34:3. 



Specimens in the McGill University Museum. Labelled 

 "639." ^^ Leperditia canadensis, Trenton {?)^ Murray Bay." 



A block of black limestone, with valves and carapaces on a 

 bed-plane. The Leperditia is not the L. cayiadensis as re- 

 stricted in the Ann. & Mag. Nat. llist. November 1880, 

 p. 343, but L. fabulites (Conrad), var. louckiana, Jones, or, 

 as I am now inclined to term it, L. louckiana^. It is jV iiit;h 

 long by f\r high. This species was lirst found in the Bird's- 

 eye Limestone. 



On an unnumbered piece of rock from the same locality is 



* A somewhat similar Leperditioid fossil, but characterized by an 

 angular process at one end of the dorsal border, is the Cythere sublcevis, 

 Shuniard, Swallow's Eeport Geol. Surv. Missouri (Preliminary Report 

 on some of the principal Mines in Franklin, &c., Missouri), 1855, pt. 1, 

 p. 116, and pt. 2, p. 195, pi. B. fig, 15. This little fossil is said to belong 

 to " the Calciferous Sandrock under the Trenton Limestone,' having been 

 found in the "1st Magnesian Limestone,'' near its junction with Sac- 

 charoidal Sandstone, near Hiiuiilton Creek, St.-IiOuis County, Missouri." 



t It seems to me quite probable that the several apparently varietal 

 forms of these and allitd Fntomostraca had sufiicient permanence over 

 wide areas and during k)ng periods to satisfy the requirements of a 

 " species ;" and as they are distinct enough to be catalogued as separate 

 Upes and may have had important modifications in their soft parts, they 

 can conveniently be entered us " species," avoiding the repetition of dual 

 terms. 



