JONES AND Kirkpy—On Carboniferous Ostracoda from Ireland. 177 
probably interchangeable forms, agreeing in their oblong and round-ended shape 
and incurved ventral line, we might still separate them into three groups or 
varieties. Var. 1. Incurved or hollow on both the dorsal and the ventral 
margin; ends rounded equally or nearly so (fig. 1). Var. 2. Slightly incurved 
on the back; sloping on the postero-dorsal margin; ventral incurved (fig. 4). 
Var. 3. Straight dorsal border; ventral incurved; ends rounded, having very 
slight but recognizable variations from the semicircular in different individuals 
(figs. 2, 3, and 5). All these have the valves most convex medially, and their 
edge views are lenticular or lanceolate. 
We give the new specific name on account of the gradational aspect of the 
varying amount of constriction. 
There are several published Cytherelle sub-oblong in shape, and more or less 
constricted, and in so far like the above; but none of them agree with the latter 
in profile (edge view), and slight differences can be recognized as to other 
features. 
Oblong and more or less constricted, smooth Cytherella* :— 
C. parallela, Reuss, Cretaceous; Brady, Recent. 
C. Fischeri, Terquem, Tertiary. 
C. pulchra, Brady, Recent. 
C. Scotica, Brady, Recent. 
C. Murchisoniana, Jones & Kirkby, Carboniferous. 
Cytherella Smith, a Silurian species (Ann. Mag. Nat. Hist., ser. 5, vol. xix., 1887, 
p- 192, pl. vii, figs. 15, 16), one of the more or less constricted forms, varies in 
outline even more than the species under notice. It differs from the latter, more 
especially in its edge-view. 
There are still other Cytherelle in the Cultra Shale, such as fig. 6, which 
we hesitate to name. Some, though much shorter than @. attenuata, approach it, 
one end being obliquely truncate, and the other obliquely rounded. 
5. Cytherella simplex (?), Jones, Kirkby, and Brady. 
1884. Cytherella simplex, . . Jones, Kirxpy, & Brapy, ‘‘ Monogr. Brit. Carb. 
Entom.,” Pal. Soc., p. 75, pl. vii, fig. 3a, b. 
1886. rs 3 Jones & Kirxpy, Quart. Journ. Geol. Soc., vol. xlii., 
p- 509. 
Of the many published figures of oval and suboval Cytherelle, from the 
Carboniferous and other formations, none of them corresponds with this specimen 
* See ‘‘ Monograph Brit. Foss. Biy. Entom. Carbonif.,”’ Pal. Soc. 1884, pp. 57-69. 
