236 VINE: CAEBONIFEEOUS ENTOMOSTRACA, ETC. 
and 66. In that work Kirhhya Permiana Jones, received the name 
of Dithyrocaris. Since then, the discovery of a number of species in 
the Carboniferous rocks have necessitated a change in the name, and 
the present one is instituted in honour of Mr. Kirkby, the indefat- 
igable coadjutor, with Mr. Jones in their united labours on the 
Carboniferous and Permian Entomostraca especially. 
" The carapace valves are flattish, thick, oblong, impressed with 
a sub -central pit, and raised hito ridges, some concentric with the 
margin, associated sometimes with longitudinal riblets, or wrinkles, 
and often accompanied by a reticulate ornament. In shape, the 
valves are sub-oblong, usually higher behind than before, the extrem- 
ities are more or less rounded, but one often much more obliquely 
than the other ; the dorsal border is straight, and its ends are sub- 
acute." — T. Rupert Jones' Monthly Micro. Jour., Oct. 1870. 
The valves of this genus in some respects resemble those of 
SeyWcAm, " but the double and sometimes threefold ventral rims, 
and especially the sub-central pit and longitudinal riblets, distinguish 
them." — Ibid. I have not found more than three species in the 
shales of Hurst, and specimens of these are rare. 
9. KiRKBYA PERMIANA, Joiies, (PI. XIL. figs. 12 and 12a.) 
Dithyrocaris Permiana, Jones, Permian Foss., p. GG, tab. XVIII., 
fig. 1, a, b, c, d. 
The Carboniferous specimens of this species are much finer than 
the Permian, and their abundance in the shales of Scotland, and even 
in some of the Northumberland shales, enable the investigator to 
study the form with much greater advantage. But, so far as my 
own experience enables me to give an opinion, the species are very 
rare in the Yorkshire shales. I have only about five specimens in 
my collection, and these correspond so closely with the described 
species that I think there can be no doubt about the identity. The 
specimens figured (fig. 12) though magnified the same number of 
diameters, is smaller than fig. la Perm. Foss., pi. XVIII., but rather 
broader than the cast Id'm the same plate. Some of the Yorkshire 
specimens are either crushed or broken ; but the general form of 
the valves are sufficiently characteristic to enable the student to 
identify the species when found.* 
* Since the above was written I have found more specimens of this Kirkhya, 
but I allow the original to stand, because, from my first specimen, the figures 12 
and 12a are drawn, one magnified 50, the other 25 diameters. 
