40 Messrs. Jones and Kirkby on Carboniferous Entomostraca. 
forms described in our former memoir, it will be convenient to 
retain the name as that of a variety. 
In the second part of his ‘ Verstein. Grauwacken Sachsens’ 
(1853), p. 23, Dr. Geinitz described a small Bivalve Entomostra- 
can, which he termed ‘ Cytherina subrecta, Portlock,’ and which 
he found at the Gunzenberg, near Plauen, in company with the 
tail-spines of Dithyrocaris Murchisoni; and he remarked that, 
as Portlock found his specimens with Dithyrocaris, the circum- 
stances are alike for the Silurian and the Carboniferous organ- 
isms. But Geinitz’s Cytherina subrecta, as illustrated by him at 
pl. 19. fig. 20 of the work above referred to, is very different 
in appearance from Portlock’s C. suwbrecta, being narrower in 
proportion, zrcurved both on the dorsal and ventral margins, 
bordered by a flat rim (apparently) all round, and rounded 
equally at the ends. The Silurian spines of the so-called 
“ Dithyrocaris ” are very probably those of Ceratiocaris. 
Leperditia Okeni of the size and form of L. subrecta occurs 
at Fermanagh, Ireland (Portlock); Blackwell, near Bristol 
(Moore); Great Orme’s Head (Dr. Holl) ; Whorlton, Teesdale 
(Parker) ; Wyebourne, Cumberland (Bland); banks of the 
Wansbeek (Pecket) ; Barnard Castle (Barron) ; Carluke (Hunter); 
West Broadstone, Ayrshire (Thomson) ; Orchard, near Thorn- 
liebank (Armstrong); Gare, Carluke (Thomson); Howrat 
Quarry, near Dalry (Armstrong); Craigenglen (Young and 
Crosskey) ; Campbeltown (Thomson) ; Carboniferous Limestone, 
Ashford, Derbyshire (Geol. Survey); Carboniferous Shales, 
half a mile south of Mitcheldean (Geol. Survey) ; and at many 
places in Ireland (Griffith and Geological Surveyors). See further 
on. 
1844. M*‘Coy.—In 1844 Professor M‘Coy considerably en- 
larged our knowledge of the Entomostraca of the Carboniferous 
Rocks by the description and illustration of twenty-two forms 
(including Hntomoconchus Scouleri), besides two species of 
Dithyrocaris (D. Scoulert and D. tenuistriatus), all from the 
Lower Carboniferous strata of Ireland. 
Thanks to the courtesy of Sir Richard Griffith, Bart., we have 
been enabled to examine many of the specimens described by 
Prof. M‘Coy, and thereby to make our comparisons more surely. 
The localities of nearly all the specimens described by M‘Coy 
(and all that we have had in hand) have been given by Sir R. 
Griffith in the ‘ Journal Geol, Soc, Dublin,’ vol, ix. (1860), pp. 
21 &c.; and indeed the specimens retain their original labels, 
with the localities indicated, 
On comparing the specimens with the figures in the ‘ Synopsis 
of the Characters of the Mountain-Limestone Fossils of Ireland,’ 
pl. 23. figs, 4-25, we fail in recognizing several of M‘Coy’s 
