26 PROF. T. R. JONES ON" SOME PALEOZOIC OSTRACODA 



(pi. Ixxix. A, figs. 6 a-e, not j^ublished) ; and Leperditia Jonesi, p. 372 

 (figs. 7 ci-e, not published). 



Leperditia alta [var.], Dana, ' Text-book of Geology/ 1870, p. 98, 

 fig. 175 (reversed) ; ' Manual of Geologj^,' 3rd edit. 1874, p. 2^9, 

 fig. 473. 



Leperditia alta, Meek, * Geol. Survey Ohio,' 1873, p. 187, pi. xvii. 

 figs. 2 a [Jonesi\ 2 b [alta]. 



Leperditia alta, Jones, 'Ann. & Mag. N. H.' ser. 5, vol. viii. 1881, 

 pp. 345, 346. 



Leperditia alta, Whitfield, ' Geology of Wisconsin,' vol. i. 1883, 

 p. 198, fig. e [alta, var.]; vol. iv. 1882, p. 323, pi. xxv.figs. 8 & 9 [aUa'\. 



Leperditia alta, Jones, •■ Ann. & Mag. N. H.' ser. 5, vol. xiv. 1884, 

 pp. 342-344. 



Size : — 



Leugth. Height. Thickness, 



uiin. mm. mm. 



PI. I. fig. 6 9 6 {L, alta, var.). 



Pal. N.Y. vol. ii.pl. Ixxviii. : 



fig. 2 c 18 11| {L. Jonesi?). 



fig. 26 12 7 ] ,r 7. ^ 



fig.2a 5 2i \{L.alta), 



These are described as " individuals of different size " ; and 

 therefore are figured probably of the natural size. 



A.&M.N.H.1856, pl.vii.: 



fig. 6 8| 6 5 {L. Jonesi) ] Arctic 



fig. 7 5 3 2 {L. alta) J Regions. 



A.&M.N.H. 1858,pl. X 



f I (Z. aZ^rt)Pennsyl 



Geol. Surv. Ohio, 1873, pi. xvii. : 



fig. 2 a lOi 7J 



" i H 



fig. 9 8 U y ,r 7. x-D 1 • 



^^ o A Qi M//.««rt) Pennsylvania. 



^ 2 6 llf «^ 



g:"-^}o'^- 



Some confusion exists in the definition and nomenclature of these 

 species. The drawing in Vanuxem's work is very bad, but Prof. 

 Hall retained the specific name (with some doubt) for the four spe- 

 cimens which he described and figured in the 'Palaeontol. New York,' 

 vol. ii. 1852, p. 338, pi. Ixxviii. figs. 2 a, h, c, d. 



1. In 1859, ' Pal. N. Y.' vol. iii. p. 372, one of the forms usually 

 associated with L. alia was separated by Prof. Hall as Leperditia 

 Jonesi, being of larger size and greater proportional height, more 

 convex centrally, and becoming papillose (part of a valve, fig. 2 d) 

 on the surface when weathered. If we take fig. 2 c for this species, 

 it is oblicjiiely subovate, well rounded behind, and curving obliquely 

 upwards and forwards in front ; the valve is therefore higher 

 behind than in front . It is straight on the back, with its hinge- 

 line much shorter than the full length of the valve (pro]jortion : 



