306 On the Paleozoic Bivalved Entomostraca. 
10. Batrdia grandis, Jones and Kirkby. 
(GEA SGA aa ee LS) 
Bairdia grandis, J. & K., Quart. Journ. Geol. Soc. vol. xxxv. 1879, 
p. 572, pl. xxix. figs. 1 and 2. 
Of B. grandis, as known in Carboniferous strata, there are 
several finely developed and characteristic specimens in this 
collection, the one figured being one of the best. 
Whether this robust form of Bazrdia is exactly the same 
as the Permian Ostracod described and figured by one of us 
in 1859 as B, plebeia, Reuss, var. grandis, is not quite clear, 
for the latter is only known to have occurred once, and then 
in an imperfect condition. There is no doubt, however, as to 
these Mongolian specimens being the same as the Carbon- 
iferous Ostracod which we here and elsewhere refer to as 
B. grandis. ‘They are the same in size, general form, 
thickness of the shell, and other particulars characteristic of 
the species. 
BL. grandis occurs in the Carboniferous- Limestone series of 
Scotland, and less rarely in the same series of the north of 
England. 
11. Bairdia Hisingeri? (Miinster), var. Mongoliensis. 
(Pl. XVI. fig. 13.) 
Bairdia Hisingert (Minster), Jones and Kirkby, Quart. Journ. Geol. 
Soe. vol. xxxv. 1879, p. 570, pl. xxix. figs. 4-10. 
Besides the species already noticed there is another form 
that scarcely agrees with any described Bairdie. It is 
probably nearest to B. Hisingert, with which, as a variety, 
we place it at present. It differs from good examples of that 
species in the dorsal border being straight in the middle and 
then inclined strongly to the front, also in its longer and more 
definite anterior and posterior slopes, and in its more rounded 
anterior extremity. Its carapace is thus highest at the ante- 
rior third, and its general form is decidedly more elegant 
than that of B. Hisingertd proper. We distinguish it as 
var. Mongoliensis. 
EXPLANATION OF PLATE XVI. 
(All the figures are magnified about 25 diameters.) 
Fig. 1. Leperditia Okeni (Minster). Carapace, showing left valve. 
Fig. 2. Leperditia Okeni (Minster), var. mornata (M‘Coy). Carapace, 
showing left valve. ; 
Fig. 3. Bythocypris bilobata (Munster), Carapace, showing right valve. 
