Lower- Carboniferous Entomostraca. Bj/ T. R. Jones. 317 



figui-ed and described in the •' Ann. Mag. N. H.' ser. 3, vol. i., 

 p. 244, pi. 9, in which a simple furrow and a tendency to a 

 Leperditia-like form are characteristic." These were referred 

 by Dr. HoU and myself in 1865 ("Ann. Mag. N. H.," ser. 3, vol. 

 XVI, p, 417) to the genus Primitia ; but I do not wish to transfer 

 Mr Tate's little fossil to the last-mentioned genus for several 

 reasons. 



In the first place, the dorsal line in my woodcut, fig. 3, p. 88, 

 ends too sharply at the narrower (posterior?) portion of the 

 valve, — giving the valve too much of a Leperditioid appearance ; 

 in fact, the specimens have a less pronounced hinge-line, and 

 less oblong valves (that is, with less equal ends), than the figure 

 shews. Thus they now appear to me to be much less Leper- 

 ditioid, and much more Oytheroid, that is, ovate-oblong, with the 

 anterior portion broader than the posterior, and the dorsal much 

 straighter than the ventral margin ; the dorsal line, also, falls 

 into its anterior slope (or stops at the front hinge- joint) at about 

 a fourth of the length of the valve from the broadest end, and 

 loses its straightness more imperceptibly near the hinder end of 

 the valve. The transverse sulcus impressed on the mid-dorsal 

 region of each valve is not, however, known in recent Cytherce ; 

 but it is characteristic of Limnicy there, and occurs also in some 

 other recent Entomostracans of estuarine or freshwater habitats, 

 — namely Cyprideis {CytherideaJ, and in one Cypris (G. gibha, 

 Eamdohry. These dorso-sulcate valves of Oyprids and Cytherids 

 exhibit also the general ovate-oblong outline described above as 

 that shewn by the fossil specimens under notice. 



Thus, then, our fossil specimens are neither Beyrichice nor 

 PrimiticB^ ; nor can we regard them as belonging to Gythere. 



Placed with its anterior (broadest) end upwards (as usual in 

 depicting Cy//«(?r^ and its allies), the so-called "-^ Beyrichia''' Tatei 

 reminds us of some existing forms of Cypris, Cyprideis, and Lim- 

 nicythere ; and it corresponds with them in appearance far better 

 than it agrees with any Beyrichian form, and even better than 

 wi th the Primitim to which I once thought it might be assimilated. 

 Nevertheless it differs from all in some essential particulars ; and, 

 though it may have some relationship with the freshwater and 

 hrachish lUmnicy there and other dorso-sulcate forms above men- 

 tioned, yet the apparent alliance is not close enough to allow of 



*I mentioned this as a likely collocation in the "Ann. Mag. N.H.'' 

 November 1882, p. 369. 



