158 ON PERMIAN ENTOMOSTRACA FROM 



Cretaceous Entomostraca of England," 1849; in that of the 

 "Tertiary Entomostraca" (Paleeont. Soc, 185G); and in Mr. 

 Kirkby's memoir preceding this notice. 



I find, on breaking up the remaining fragments of magnesian 

 limestone (from Byers' Quarry), with which Professor King 

 favoured me in 1847-8, and also by reference to my first draw- 

 ings, that I have some additional materials of which I can make 

 use with advantage in improving and adding to my notices of 

 the species; especially in reminding me of those links of varia- 

 tion which I regarded as existing within the limits of certain 

 species, some of the typical forms of which I gave in my figures. 



In my former descriptions of these Entomostraca^ I doubtfully 

 placed some with Cythereis and Cytherella. But I think it better 

 to withdraw these provisional references, until we know some- 

 thing more certain of the fossil species, and, in the meantime, I 

 use the genus Cythere in its fullest sense. The Bairdice, how- 

 ever, are so characteristically featured, that we have seldom any 

 difficulty in determining the individuals belonging to this sub- 

 genus. 



By the Idndness of Sir E. Griffith, I have been enabled to ex- 

 amine, at my leisure, the specimen on which the species 

 Bairdia curta was determined by M'Coy. Mr. Kirkby has 

 already noticed (p. 142) its characteristic features as contrasted 

 with B. pleheia. 



I regret that it has not yet been in my power to compare the 

 Carboniferous Entomost7Xica described by Count Munster with 

 those before us. It is very desirable that we should have more 

 than a few words of description, as the means of comparison in 

 determining the C. elongata. 



Dr. Richter having favoured me with a series of specimens 

 from Saalfeld, and also with some remarks on them, I am en- 

 abled to correlate his figures with our own. 



CYTHERE, 3Iuller. 



1 . C. MoRRisiANA, Jones. PI. XL, figs, la, Ih, Ic. 



Cythere Morrisiana. Jones, in " King's Monograph 

 Perm. Foss.," p. 61, pi. 18, figs. 2a, 2h, 2c, 

 Carapace irregularly oblong, convex, smooth; dorsal and 



