Paleozoic Bivalved Entomostraca. 457 
gill, Settle ; and the geological positionsis the Carboniferous 
Limestone. Thus the species occur lower in the series 
(earlier in time) than those from Hurst and Downholme. 
a 
| List of Species from Dowgill (Carboniferous Limestone). 
. Leperditia Okeni (Miinster) *. 
Armstrongiana, J. & K.* 
. Kirkbya permiana, Jones *. 
umbonata (d’Kichwald), Ann. & Mag. Nat. Hist. ser. 5, 
vol, xv. 1885, p. 180, pl. iii. fig. 2. 
. Bairdia plebeia*, var. alta, nov. (Pl. XXL. fig. 6.) 
Hisingert (Munster) *, 
—— Hisingert (Minster) *, var. contracta, noy. (Pl. XXI. fig. 7.) 
submucronata, J. & K.* 
— bgevis, J. & K.* 
. Bythocypris bilobata (Minster) *. 
. Argillecia (Bythocypris?) equalis, J. & K.*, var. acuta, nov. 
(Pl. XXI. fig. 8.) 
12. Bythocypris? breviata, sp.n. (Pl. XXI. fig. 9.) 
pod 
SOON Poor 
— 
= 
The Bairdie here referred to as nos. 5 and 7 are related to 
B, plebeia and B. Hisingeri ; and somewhat similar forms are 
not rare in some Lower-Carboniferous localities, and have been 
referred to in former papers as Bairdia grandis or its varieties. 
No. 5 (Pl. XXI. fig. 6) is a relatively short and high variety 
of B. plebeia, with angular dorsal margin, taking fig. 11, 
pl. xxviii. Quart. Journ. Geol. Soc. vol. xxxv. 1879, asa 
type. It is from 75 to 7 inch in length, less than one and a 
half times its height, which is greatest at the anterior third. 
Subpentagonal in outline. Dorsal border short and straight 
on the hinge-line, sloping at the anterior extremity, and 
joining the sharp posterior angle with an elegant hollow 
curve. Ventral border gently sinuous, curving up anteriorly 
to form the bluntly projecting end of the valve in front. We 
term this variety B. plebeta, var. alta, nov. 
No. 7 (Pl. XXI. fig. 7) is a relatively short and high form 
of B. Hisingert, with the front end rounded as in the modifi- 
cation of this species figured in Quart. Journ. Geol. Soe. 
vol. xxxv. pl. xxix. fig. 9. Suboblong in outline, with one 
end (anterior) rounded ; the other obliquely truncate, ending 
below in a blunt prow-like angle ; dorsal edge feebly convex, 
rounding off at the ends; ventral border gently sinuous. We 
regard this as B. Hisingeri, var. contracta, nov. 
Argillecia (Bythocypris ?) equalis derived its specific name 
from its nearly equally rounded extremities. But in some 
* Also from Hurst or Downholme ; see pp. 453 & 455. Carboniferous 
Bairdie are often difficult of determination. As in the present instance 
one of us holds the opinion that the Bairdia fig. 6 would be as well left 
with B. grandis as placed as a variety of B, plebeia.—J. W. K. 
